@article{lecroy_ghosh_untilova_guio_stone_brinkmann_luscombe_spano_salleo_2024, title={Polaron absorption in aligned conjugated polymer films: breakdown of adiabatic treatments and going beyond the conventional mid-gap state model}, ISSN={2051-6347 2051-6355}, url={http://dx.doi.org/10.1039/d3mh01278f}, DOI={10.1039/D3MH01278F}, abstractNote={This work resolves the inter- and intramolecular polarized absorption of polarons in the organic semiconductor P3HT, allowing previous theoretical predictions to be tested. Vibronic coupling is shown to be crucial in understanding polaron absorption.}, journal={Materials Horizons}, publisher={Royal Society of Chemistry (RSC)}, author={LeCroy, Garrett and Ghosh, Raja and Untilova, Viktoriia and Guio, Lorenzo and Stone, Kevin H. and Brinkmann, Martin and Luscombe, Christine and Spano, Frank C. and Salleo, Alberto}, year={2024} }
 @article{ghosh_paesani_2023, title={Connecting the dots for fundamental understanding of structure–photophysics–property relationships of COFs, MOFs, and perovskites using a Multiparticle Holstein Formalism}, volume={14}, ISSN={2041-6520 2041-6539}, url={http://dx.doi.org/10.1039/d2sc03793a}, DOI={10.1039/D2SC03793A}, abstractNote={The Multiparticle Holstein Formalism is a promising theoretical framework that efficiently bridges the gap between theory and experiments.}, number={5}, journal={Chemical Science}, publisher={Royal Society of Chemistry (RSC)}, author={Ghosh, Raja and Paesani, Francesco}, year={2023}, pages={1040–1064} }
 @article{pan_ho_paesani_ghosh_2023, title={Engineering Flat and Dispersive Bands in 2D Layered COFs via Interlayer Stacking and Donor–Acceptor Strategy}, volume={35}, ISSN={0897-4756 1520-5002}, url={http://dx.doi.org/10.1021/acs.chemmater.3c00510}, DOI={10.1021/acs.chemmater.3c00510}, abstractNote={Covalent organic frameworks (COFs) are an emergent class of two-dimensional (2D) crystalline organic materials that exhibit unique electronic, optical, and transport properties. In this study, we employ density functional theory (DFT) and the multiparticle Holstein formalism (MHF) to investigate the electronic structure and two-dimensional coherence of polarons in donor-acceptor COFs as a function of interlayer stacking arrangement. We show that simple modifications in the interlayer stacking arrangement have a profound impact on the transport properties, which can range from metallic behavior with vanishing band gap to highly localized states having completely flat bands. The extent of charge delocalization is found to be sensitive to the type of stacking arrangement and the precise arrangement of the donor and acceptor fragments within the COF structure. The results from the DFT calculations are consistent with MHF-based simulations, demonstrating that stacking-induced interlayer interactions facilitate better in-plane charge delocalization. As a consequence, we find that interlayer interactions help circumvent defect-induced trap states to enhance overall charge delocalization. Based on these analyses, we conclude that interlayer stacking can be exploited to guide the design of new 2D layered COF structures with potential applications in organic electronics.}, number={16}, journal={Chemistry of Materials}, publisher={American Chemical Society (ACS)}, author={Pan, Yuanhui and Ho, Ching-Hwa and Paesani, Francesco and Ghosh, Raja}, year={2023}, month={Aug}, pages={6235–6245} }
 @article{balooch qarai_ghosh_hestand_spano_2023, title={Multipolaron Complexes in Conducting Polymers: The Importance of Hole–Hole Repulsion in Charge Delocalization}, volume={127}, ISSN={1932-7447 1932-7455}, url={http://dx.doi.org/10.1021/acs.jpcc.3c00289}, DOI={10.1021/acs.jpcc.3c00289}, abstractNote={Multipolaron complexes in p-doped poly(3-hexylthiophene) films are investigated theoretically for polaron-anion configurations in which stationary dopant anions are positioned on both sides of the polymer chain, within the lamellar region. Complexes as large as tetrapolarons, consisting of four anions and an equal number of mobile holes, are considered. It is found that the mid-IR absorption band (P1) red-shifts and the hole ionization potential decreases as the complex grows in size, from a single polaron to a tetrapolaron. Such behavior is shown to arise mainly from enhanced hole delocalization due to hole–hole repulsion and has important implications for charge transport in organic materials.}, number={13}, journal={The Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Balooch Qarai, Mohammad and Ghosh, Raja and Hestand, Nicholas J. and Spano, Frank C.}, year={2023}, month={Mar}, pages={6414–6424} }
 @article{chen_jacobs_kang_lin_jellett_kang_lee_huang_baloochqarai_ghosh_et al._2023, title={Observation of Weak Counterion Size Dependence of Thermoelectric Transport in Ion Exchange Doped Conducting Polymers Across a Wide Range of Conductivities}, volume={13}, ISSN={1614-6832 1614-6840}, url={http://dx.doi.org/10.1002/aenm.202202797}, DOI={10.1002/aenm.202202797}, abstractNote={Abstract}, number={9}, journal={Advanced Energy Materials}, publisher={Wiley}, author={Chen, Chen and Jacobs, Ian E. and Kang, Keehoon and Lin, Yue and Jellett, Cameron and Kang, Boseok and Lee, Seon Baek and Huang, Yuxuan and BaloochQarai, Mohammad and Ghosh, Raja and et al.}, year={2023}, month={Jan} }
 @article{robinson_ghosh_egan_riera_knight_paesani_hassanali_2022, title={The Behavior of Methane-Water Mixtures Under Elevated Pressures Using Many-Body Potentials}, volume={3}, url={http://dx.doi.org/10.26434/chemrxiv-2022-sk6r0}, DOI={10.26434/chemrxiv-2022-sk6r0}, abstractNote={Non-polarizable empirical potentials have been shown not to be able to capture the mixing of methane–water mixtures at elevated pressures. Although DFT-based ab initio simulations may circumvent this discrepancy, they are limited in terms of the relevant time and length scales associated with mixing phenomena. Here we show that the many-body MB-nrg potential, designed to reproduce methane–water interactions with coupled cluster accuracy, successfully captures this phenomenon up to 3 GPa and 500 K with varying methane concentration. Two-phase simulations and long time scales that are required to fully capture the mixing, affordable due to the speed and accuracy of the MBX software, are assessed. Constructing the methane–water equation of state across the phase diagram shows that the stable mixtures are denser than the sum of their parts at a given pressure and temperature. We find that many-body polarization plays a central role, enhancing the induced dipole moments of methane by 0.20 D during mixing under pressure. Overall, the mixed system adopts a denser state, which involves a significant enthalpic driving force as elucidated by a systematic many-body energy decomposition analysis.}, journal={[]}, publisher={American Chemical Society (ACS)}, author={Robinson, Victor Naden and Ghosh, Raja and Egan, Colin E. and Riera, Marc and Knight, Christopher and Paesani, Francesco and Hassanali, Ali}, year={2022}, month={Mar} }
 @article{robinson_ghosh_egan_riera_knight_paesani_hassanali_2022, title={The behavior of methane–water mixtures under elevated pressures from simulations using many-body potentials}, volume={156}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/5.0089773}, DOI={10.1063/5.0089773}, abstractNote={Non-polarizable empirical potentials have been proven to be incapable of capturing the mixing of methane–water mixtures at elevated pressures. Although density functional theory-based ab initio simulations may circumvent this discrepancy, they are limited in terms of the relevant time and length scales associated with mixing phenomena. Here, we show that the many-body MB-nrg potential, designed to reproduce methane–water interactions with coupled cluster accuracy, successfully captures this phenomenon up to 3 GPa and 500 K with varying methane concentrations. Two-phase simulations and long time scales that are required to fully capture the mixing, affordable due to the speed and accuracy of the MBX software, are assessed. Constructing the methane–water equation of state across the phase diagram shows that the stable mixtures are denser than the sum of their parts at a given pressure and temperature. We find that many-body polarization plays a central role, enhancing the induced dipole moments of methane by 0.20 D during mixing under pressure. Overall, the mixed system adopts a denser state, which involves a significant enthalpic driving force as elucidated by a systematic many-body energy decomposition analysis.}, number={19}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Robinson, Victor Naden and Ghosh, Raja and Egan, Colin K. and Riera, Marc and Knight, Christopher and Paesani, Francesco and Hassanali, Ali}, year={2022}, month={May} }
 @article{yue_riera_ghosh_panagiotopoulos_paesani_2022, title={Transferability of data-driven, many-body models for CO2 simulations in the vapor and liquid phases}, volume={156}, url={https://doi.org/10.1063/5.0080061}, DOI={10.1063/5.0080061}, abstractNote={Extending on the previous work by Riera et al. [J. Chem. Theory Comput. 16, 2246–2257 (2020)], we introduce a second generation family of data-driven many-body MB-nrg models for CO2 and systematically assess how the strength and anisotropy of the CO2–CO2 interactions affect the models’ ability to predict vapor, liquid, and vapor–liquid equilibrium properties. Building upon the many-body expansion formalism, we construct a series of MB-nrg models by fitting one-body and two-body reference energies calculated at the coupled cluster level of theory for large monomer and dimer training sets. Advancing from the first generation models, we employ the charge model 5 scheme to determine the atomic charges and systematically scale the two-body energies to obtain more accurate descriptions of vapor, liquid, and vapor–liquid equilibrium properties. Challenges in model construction arise due to the anisotropic nature and small magnitude of the interaction energies in CO2, calling for the necessity of highly accurate descriptions of the multidimensional energy landscape of liquid CO2. These findings emphasize the key role played by the training set quality in the development of transferable, data-driven models, which, accurately representing high-dimensional many-body effects, can enable predictive computer simulations of molecular fluids across the entire phase diagram.}, number={10}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Yue, Shuwen and Riera, Marc and Ghosh, Raja and Panagiotopoulos, Athanassios Z. and Paesani, Francesco}, year={2022}, month={Mar}, pages={104503} }
 @article{moulé_gonel_murrey_ghosh_saska_shevchenko_denti_fergerson_talbot_yacoub_et al._2021, title={Quantifying Polaron Mole Fractions and Interpreting Spectral Changes in Molecularly Doped Conjugated Polymers}, volume={8}, ISSN={2199-160X 2199-160X}, url={http://dx.doi.org/10.1002/aelm.202100888}, DOI={10.1002/aelm.202100888}, abstractNote={Abstract}, number={4}, journal={Advanced Electronic Materials}, publisher={Wiley}, author={Moulé, Adam J. and Gonel, Goktug and Murrey, Tucker L. and Ghosh, Raja and Saska, Jan and Shevchenko, Nikolay E. and Denti, Ilaria and Fergerson, Alice S. and Talbot, Rachel M. and Yacoub, Nichole L. and et al.}, year={2021}, month={Dec}, pages={2100888} }
 @article{ghosh_paesani_2021, title={Topology-Mediated Enhanced Polaron Coherence in Covalent Organic Frameworks}, url={https://doi.org/10.33774/chemrxiv-2021-tb31g}, DOI={10.33774/chemrxiv-2021-tb31g}, abstractNote={We employ the Holstein model for polarons to investigate the relationship among defects, topology, Coulomb trapping, and polaron delocalization in covalent organic frameworks (COFs). We find that intra-sheet topological connectivity and pi-column density can override disorder-induced deep traps and significantly enhance polaron migration by several orders of magnitude in good agreement with recent experimental observations. The combination of percolation networks and micropores makes trigonal COFs ideally suited for charge transport followed by kagome/tetragonal, and hexagonal structures. By comparing the polaron spectral signatures and coherence numbers of large 3D frameworks having a maximum of 180 coupled chromophores, we show that controlling nanoscale defects and the location of the counter anion is critical for the design of new COF-based materials yielding higher mobilities. Our analysis establishes design strategies for enhanced conductivity in COFs which can be readily generalized to other classes of conductive materials such as metal-organic frameworks and perovskites.}, author={Ghosh, Raja and Paesani, Francesco}, year={2021}, month={Jul} }
 @article{ghosh_paesani_2021, title={Topology-Mediated Enhanced Polaron Coherence in Covalent Organic Frameworks}, volume={12}, ISSN={1948-7185 1948-7185}, url={http://dx.doi.org/10.1021/acs.jpclett.1c02454}, DOI={10.1021/acs.jpclett.1c02454}, abstractNote={We employ the Holstein model for polarons to investigate the relationship among defects, topology, Coulomb trapping, and polaron delocalization in covalent organic frameworks (COFs). We find that intrasheet topological connectivity and π-column density can override disorder-induced deep traps and significantly enhance polaron migration by several orders of magnitude in good agreement with recent experimental observations. The combination of percolation networks and micropores makes trigonal COFs ideally suited for charge transport followed by kagome/tetragonal and hexagonal structures. By comparing the polaron spectral signatures and coherence numbers of large three-dimensional frameworks having a maximum of 180 coupled chromophores, we show that controlling nanoscale defects and the location of the counteranion is critical for the design of new COF-based materials yielding higher mobilities. Our analysis establishes design strategies for enhanced conductivity in COFs that can be readily generalized to other classes of conductive materials such as metal–organic frameworks and perovskites.}, number={39}, journal={The Journal of Physical Chemistry Letters}, publisher={American Chemical Society (ACS)}, author={Ghosh, Raja and Paesani, Francesco}, year={2021}, month={Sep}, pages={9442–9448} }
 @article{ghosh_paesani_2021, title={Topology-Mediated Enhanced Polaron Coherence in Covalent Organic Frameworks}, url={https://doi.org/10.26434/chemrxiv-2021-tb31g}, DOI={10.26434/chemrxiv-2021-tb31g}, abstractNote={We employ the Holstein model for polarons to investigate the relationship among defects, topology, Coulomb trapping, and polaron delocalization in covalent organic frameworks (COFs). We find that intra-sheet topological connectivity and pi-column density can override disorder-induced deep traps and significantly enhance polaron migration by several orders of magnitude in good agreement with recent experimental observations. The combination of percolation networks and micropores makes trigonal COFs ideally suited for charge transport followed by kagome/tetragonal, and hexagonal structures. By comparing the polaron spectral signatures and coherence numbers of large 3D frameworks having a maximum of 180 coupled chromophores, we show that controlling nanoscale defects and the location of the counter anion is critical for the design of new COF-based materials yielding higher mobilities. Our analysis establishes design strategies for enhanced conductivity in COFs which can be readily generalized to other classes of conductive materials such as metal-organic frameworks and perovskites.}, journal={ChemRxiv}, author={Ghosh, Raja and Paesani, Francesco}, year={2021}, month={Jul} }
 @article{yue_riera_ghosh_panagiotopoulos_paesani_2021, title={Transferability of data-driven, many-body models for CO<sub>2</sub> simulations in the vapor and liquid phases}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85126196133&partnerID=MN8TOARS}, DOI={10.26434/chemrxiv-2021-0ql9t}, abstractNote={Extending on previous work by Riera et al. [J. Chem. Theory Comput. 16, 2246 (2020)], we introduce a second generation family of data-driven many-body MB-nrg models for CO2 and systematically assess how the strength and anisotropy of the CO2-CO2 interactions affect the models' ability to predict vapor, liquid, and vapor-liquid equilibrium properties. Building upon the many-body expansion formalism, we construct a series of MB-nrg models by fitting 1-body and 2-body reference energies calculated at the coupled cluster level of theory for large monomer and dimer training sets. Advancing from the first generation models, we employ the Charge Model 5 scheme to determine the atomic charges and systematically scale the 2-body energies to obtain more accurate descriptions of vapor, liquid, and vapor-liquid equilibrium properties. Comparisons with the polarizable TTM-nrg model, which is constructed from the same training sets as the MB-nrg models but using a simpler representation of short-range interactions based on conventional Born-Mayer functions, showcase the necessity of high dimensional functional forms for an accurate description of the multidimensional energy landscape of liquid CO2. These findings emphasize the key role played by the training set quality and flexibility of the fitting functions in the development of transferable, data-driven models which, accurately representing high-dimensional many-body effects, can enable predictive computer simulations of molecular fluids across the entire phase diagram.}, journal={ChemRxiv}, author={Yue, S. and Riera, M. and Ghosh, R. and Panagiotopoulos, A.Z. and Paesani, F.}, year={2021} }
 @article{qarai_ghosh_spano_2021, title={Understanding Bipolarons in Conjugated Polymers Using a Multiparticle Holstein Approach}, volume={125}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85118927669&partnerID=MN8TOARS}, DOI={10.1021/acs.jpcc.1c06767}, number={44}, journal={Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Qarai, M.B. and Ghosh, R. and Spano, F.C.}, year={2021}, pages={24487–24497} }
 @article{ghosh_paesani_2021, title={Unraveling the effect of defects, domain size, and chemical doping on photophysics and charge transport in covalent organic frameworks}, volume={12}, ISSN={2041-6520 2041-6539}, url={http://dx.doi.org/10.1039/d1sc01262b}, DOI={10.1039/D1SC01262B}, abstractNote={This study highlights the importance of mid-infrared spectral signatures and discusses the fundamental mechanisms driving charge transport in COFs. Our analysis can hopefully guide the rational design of new COFs yielding higher conductivities.}, number={24}, journal={Chemical Science}, publisher={Royal Society of Chemistry (RSC)}, author={Ghosh, Raja and Paesani, Francesco}, year={2021}, pages={8373–8384} }
 @article{ghosh_paesani_2021, title={Unraveling the effect of defects, domain size, and chemical doping on photophysics and charge transport in covalent organic frameworks}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85103331963&partnerID=MN8TOARS}, DOI={10.26434/chemrxiv.14101535}, abstractNote={We present a novel theoretical
approach to understanding the effect of electronic defects, domain size, and chemical
dopants on the infrared spectral line shape and three-dimensional charge
transport of positively charged polarons (“holes”) in doped (and undoped) Covalent
Organic Frameworks (COFs). The simulated spectra are in excellent agreement
with very recent measurements conducted on Iodine doped COF films. Through a
detailed systematic analysis, we can also determine the polaron coherence
lengths both along the 2D COF plane (intraframework) and through the molecular
columns (interframework). The coherence lengths are important quantities in
determining the anisotropic charge mobilities and conductivities in such films
and are therefore of major interest in understanding the operation of organic
electronic devices such as transistors and solar cells. By obtaining the first
quantitative agreement with iodine doped TANG-COF, we identify well defined
spectral signatures that provides conclusive evidence on why doped COFS have so
far shown lower bulk conductivity compared to doped polythiophenes.}, journal={ChemRxiv}, author={Ghosh, R. and Paesani, F.}, year={2021} }
 @article{riera_hirales_ghosh_paesani_2020, title={Data-Driven Many-Body Models with Chemical Accuracy for CH<sub>4</sub>/H<sub>2</sub>O Mixtures}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85099007711&partnerID=MN8TOARS}, DOI={10.26434/chemrxiv.13013057.v1}, abstractNote={Many-body potential energy functions (PEFs) based on the TTM-nrg and MB-nrg theoretical/computational frameworks are developed from coupled cluster reference data for neat methane and mixed methane/water systems. It is shown that that the MB-nrg PEFs achieve subchemical accuracy in the representation of individual many-body effects in small clusters and enables predictive simulations from the gas to the liquid phase. Analysis of structural properties calculated from molecular dynamics simulations of liquid methane and methane/water mixtures using both TTM-nrg and MB-nrg PEFs indicates that, while accounting for polarization effects is important for a correct description of many-body interactions in the liquid phase, an accurate representation of short-range interactions, as provided by the MB-nrg PEFs, is necessary for a quantitative description of the local solvation structure in liquid mixtures.}, journal={ChemRxiv}, author={Riera, M. and Hirales, A. and Ghosh, R. and Paesani, F.}, year={2020} }
 @article{riera_hirales_ghosh_paesani_2020, title={Data-Driven Many-Body Models with Chemical Accuracy for CH<sub>4</sub>/H<sub>2</sub>O Mixtures}, volume={124}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85097840813&partnerID=MN8TOARS}, DOI={10.1021/acs.jpcb.0c08728}, abstractNote={Many-body potential energy functions (PEFs) based on the TTM-nrg and MB-nrg theoretical/computational frameworks are developed from coupled cluster reference data for neat methane and mixed methane/water systems. It is shown that the MB-nrg PEFs achieve subchemical accuracy in the representation of individual many-body effects in small clusters and enables predictive simulations from the gas to the liquid phase. Analysis of structural properties calculated from molecular dynamics simulations of liquid methane and methane/water mixtures using both TTM-nrg and MB-nrg PEFs indicates that, while accounting for polarization effects, is important for a correct description of many-body interactions in the liquid phase, an accurate representation of short-range interactions, as provided by the MB-nrg PEFs, is necessary for a quantitative description of the local solvation structure in liquid mixtures.}, number={49}, journal={Journal of Physical Chemistry B}, publisher={American Chemical Society (ACS)}, author={Riera, M. and Hirales, A. and Ghosh, R. and Paesani, F.}, year={2020}, pages={11207–11221} }
 @article{ghosh_spano_2020, title={Excitons and Polarons in Organic Materials}, volume={53}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85093876664&partnerID=MN8TOARS}, DOI={10.1021/acs.accounts.0c00349}, abstractNote={ConspectusExcitons and polarons play a central role in the electronic and optical properties of organic semiconducting polymers and molecular aggregates and are of fundamental importance in understanding the operation of organic optoelectronic devices such as solar cells and light-emitting diodes. For many conjugated organic molecules and polymers, the creation of neutral electronic excitations or ionic radicals is associated with significant nuclear relaxation, the bulk of which occurs along the vinyl-stretching mode or the aromatic-quinoidal stretching mode when conjugated rings are present. Within a polymer chain or molecular aggregate, nuclear relaxation competes with energy- and charge-transfer, mediated by electronic interactions between the constituent units (repeat units for polymers and individual chromophores for a molecular aggregate); for neutral electronic excitations, such inter-unit interactions lead to extended excited states or excitons, while for positive (or negative) charges, interactions lead to delocalized hole (or electron) polarons. The electronic coupling as well as the local coupling between electronic and nuclear degrees of freedom in both excitons and polarons can be described with a Holstein Hamiltonian. However, although excitons and polarons derive from similarly structured Hamiltonians, their optical signatures are quite distinct, largely due to differing ground states and optical selection rules.In this Account, we explore the similarities and differences in the spectral response of excitons and polarons in organic polymers and molecular aggregates. We limit our analysis to the subspace of excitons and hole polarons containing at most one excitation; hence we omit the influence of bipolarons, biexcitons, and higher multiparticle excitations. Using a generic linear array of coupled units as a model host for both excitons and polarons, we compare and contrast the optical responses of both quasiparticles, with a particular emphasis on the spatial coherence length, the length over which an exciton or polaron possesses wave-like properties important for more efficient transport. For excitons, the UV-vis absorption spectrum is generally represented by a distorted vibronic progression with H-like or J-like signatures depending on the sign of the electronic coupling, Jex. The spectrum broadens with increasing site disorder, with the spectral area preserved due to an oscillator strength sum rule. For (hole) polarons, the generally stronger electronic coupling results in a mid-IR spectrum consisting of a narrow, low-energy peak (A) with energy near a vibrational quantum of the vinyl stretching mode, and a broader, higher-energy feature (B). In contrast to the UV-vis spectrum, the mid-IR spectrum is invariant to the sign of the electronic coupling, th, and completely resistant to long-range disorder, where it remains entirely homogeneously broadened. Even in the presence of short-range disorder, the width of peak A remains surprisingly narrow as long as |th| remains sufficiently large, a property that can be understood in terms of Herzberg-Teller coupling. Unlike for excitons, for polarons, the absorption spectral area decreases with increasing short-range disorder σ (i.e., there is no oscillator sum rule) reflective of a decreasing polaron coherence length. The intensity of the low-energy peak A in relation to B is an important signature of polaron coherence. By contrast, for excitons, the absorption spectrum contains no unambiguous signs of exciton coherence. One must instead resort to the shape of the steady-state photoluminescence spectrum. The Holstein-based model has been highly successful in accounting for the spectral properties of molecular aggregates as well as conjugated polymers like poly(3-hexylthiophene) (P3HT) in the mid-IR and UV-vis spectral regions.}, number={10}, journal={Accounts of Chemical Research}, publisher={American Chemical Society (ACS)}, author={Ghosh, R. and Spano, F.C.}, year={2020}, pages={2201–2211} }
 @article{ghosh_luscombe_hambsch_mannsfeld_salleo_spano_2019, title={Anisotropic Polaron Delocalization in Conjugated Homopolymers and Donor-Acceptor Copolymers}, volume={31}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85072840288&partnerID=MN8TOARS}, DOI={10.1021/acs.chemmater.9b01704}, abstractNote={The shape of the mid-IR absorption spectrum provides valuable information about the “hole” polaron coherence length in doped and undoped conjugated polymer films. In poly(3-hexylthiophene) (P3HT) films, the spectrum generally consists of a narrow, low-energy peak A (700–1000 cm–1) followed by a much broader, higher-energy peak B (2500–5000 cm–1). By using a theory based on the Holstein Hamiltonian for mobile holes in P3HT, the IR line-shape is successfully reproduced for several recently measured spectra recorded in doped and undoped films, confirming the association of an enhanced peak ratio (A/B) with extended polaron coherence. Emphasis is placed on the origin of components polarized along the intra- and interchain directions and their dependence on the spatial distribution of disorder as well as the position of the dopant relative to the π-stack. The model is further adapted to treat donor–acceptor copolymers where the local HOMO energy varies periodically from donor unit to acceptor unit. The calcula...}, number={17}, journal={Chemistry of Materials}, publisher={American Chemical Society (ACS)}, author={Ghosh, R. and Luscombe, C.K. and Hambsch, M. and Mannsfeld, S.C.B. and Salleo, A. and Spano, F.C.}, year={2019}, pages={7033–7045} }
 @phdthesis{ghosh_2019, title={Spectroscopy of polarons in organic semiconductors: A new theoretical model}, school={Temple University}, author={Ghosh, R.}, year={2019} }
 @article{ghosh_chew_onorato_pakhnyuk_luscombe_salleo_spano_2018, title={Spectral Signatures and Spatial Coherence of Bound and Unbound Polarons in P3HT Films: Theory Versus Experiment}, volume={122}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85051513773&partnerID=MN8TOARS}, DOI={10.1021/acs.jpcc.8b03873}, abstractNote={The origin of the mid-infrared (IR) spectral features for hole absorption in doped poly(3-hexylthiophene) (P3HT) films is investigated theoretically and experimentally. Using a Holstein-style Hamiltonian to treat vibronic coupling involving the prominent vinyl stretching mode, the low-energy peak (A) occurring in the spectral interval 0.1–0.15 eV is found to contain a substantial (sometimes dominant) intrachain-polarized component, in contrast to the predictions of the more conventional treatments based on self-trapped, mid-gap polaron states where peak A is entirely interchain in origin. A higher-energy peak (B) located between 0.35 and 0.7 eV and largely intrachain-polarized is also obtained and associated with the conventional P1 polaron transition. Spectral signatures for polaron coherence based on peaks A and B are identified and used to analyze the molecular weight dependence of the IR spectral line shapes of P3HT doped with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane. Generally, the polaro...}, number={31}, journal={Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Ghosh, R. and Chew, A.R. and Onorato, J. and Pakhnyuk, V. and Luscombe, C.K. and Salleo, A. and Spano, F.C.}, year={2018}, pages={18048–18060} }
 @article{chew_ghosh_pakhnyuk_onorato_davidson_segalman_luscombe_spano_salleo_2018, title={Unraveling the Effect of Conformational and Electronic Disorder in the Charge Transport Processes of Semiconducting Polymers}, volume={28}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85052384540&partnerID=MN8TOARS}, DOI={10.1002/adfm.201804142}, abstractNote={Abstract}, number={41}, journal={Advanced Functional Materials}, publisher={Wiley}, author={Chew, A.R. and Ghosh, R. and Pakhnyuk, V. and Onorato, J. and Davidson, E.C. and Segalman, R.A. and Luscombe, C.K. and Spano, F.C. and Salleo, A.}, year={2018}, pages={1804142} }
 @article{chew_ghosh_shang_spano_salleo_2017, title={Sequential Doping Reveals the Importance of Amorphous Chain Rigidity in Charge Transport of Semi-Crystalline Polymers}, volume={8}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85031817429&partnerID=MN8TOARS}, DOI={10.1021/acs.jpclett.7b01989}, abstractNote={Sequential doping is a promising new doping technique for semicrystalline polymers that has been shown to produce doped films with higher conductivity and more uniform morphology than conventional doping processes, and where the dopant placement in the film can be controlled. As a relatively new technique, however, much work is needed to understand the resulting polymer-dopant interactions upon sequential doping. A combination of infrared spectroscopy and theoretical simulations shows that the dopants selectively placed in the amorphous regions in the film via sequential doping result in highly localized polarons. We find that the presence of dopants within the amorphous regions of the film leads to an increase in conjugation length of the amorphous chains upon doping, increasing film connectivity and hence improving the overall conductivity of the film compared with the conventional doping processes.}, number={20}, journal={Journal of Physical Chemistry Letters}, publisher={American Chemical Society (ACS)}, author={Chew, A.R. and Ghosh, R. and Shang, Z. and Spano, F.C. and Salleo, A.}, year={2017}, pages={4974–4980} }
 @article{scholes_yee_lindemuth_kang_onorato_ghosh_luscombe_spano_tolbert_schwartz_2017, title={The Effects of Crystallinity on Charge Transport and the Structure of Sequentially Processed F<sub>4</sub>TCNQ-Doped Conjugated Polymer Films}, volume={27}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85031803297&partnerID=MN8TOARS}, DOI={10.1002/adfm.201702654}, abstractNote={Abstract}, number={44}, journal={Advanced Functional Materials}, publisher={Wiley}, author={Scholes, D.T. and Yee, P.Y. and Lindemuth, J.R. and Kang, H. and Onorato, J. and Ghosh, R. and Luscombe, C.K. and Spano, F.C. and Tolbert, S.H. and Schwartz, B.J.}, year={2017}, pages={1702654} }
 @article{ghosh_pochas_spano_2016, title={Polaron Delocalization in Conjugated Polymer Films}, volume={120}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84973358721&partnerID=MN8TOARS}, DOI={10.1021/acs.jpcc.6b02917}, abstractNote={A theory describing the spatial coherence length of polarons in disordered conjugated polymer films is presented, revealing a simple relationship between oscillator strength of the mid-IR absorption band and the polaron coherence function. Applications are made to positively charged polarons or holes in poly(3-hexylthiophene) π-stacks where polaron delocalization occurs in essentially two dimensions: along the polymer axis (x-axis) and along the interchain stacking axis (y-axis). Based on a lattice model consisting of a 2D array of thiophene units linked electronically along the polymer axis (tintra) and between adjacent chains (tinter), a disordered 2D Holstein-style Hamiltonian is developed. The Hamiltonian includes vibronic coupling involving the polaron-forming vibrational mode responsible for aromatic/quinoidal oscillations. The hole absorption spectrum for light polarized along each axis is calculated along with the corresponding hole coherence function, CP(r). For diagonal disorder arising from a r...}, number={21}, journal={Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Ghosh, R. and Pochas, C.M. and Spano, F.C.}, year={2016}, pages={11394–11406} }
 @article{ghosh_pedicini_rao_asha_reber_mandal_2015, title={The effect of cluster size on the optical band gap energy of Zn-based metal-organic frameworks}, volume={44}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84937425684&partnerID=MN8TOARS}, DOI={10.1039/c5dt02132d}, abstractNote={We have synthesized three Metal–Organic Frameworks (MOFs) in which Zn metal ions form the secondary building unit, and 4,4′-sulfonyldibenzoic acid (SDB) serves as the ligand: [[Zn(DMF)(SDB)] (DMF), 1, [Zn3(DMF)3(SDB)3](DMF), 2 and [Zn3(OH)2(SDB)2] (DMF)2, 3, where DMF = dimethyl formamide].}, number={30}, journal={Dalton Transactions}, publisher={Royal Society of Chemistry (RSC)}, author={Ghosh, R. and Pedicini, A.F. and Rao, P.C. and Asha, K.S. and Reber, A.C. and Mandal, S.}, year={2015}, pages={13464–13468} }
 @article{ghosh_asha_pratik_datta_nath_mandal_2014, title={Synthesis, structure, photocatalytic and magnetic properties of an oxo-bridged copper dimer}, volume={4}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84901604506&partnerID=MN8TOARS}, DOI={10.1039/c4ra01886a}, abstractNote={A new paramagnetic and semiconductor copper citrate dimer exhibits photocatalytic behaviour towards organic dye degradation.}, number={41}, journal={RSC Advances}, publisher={Royal Society of Chemistry (RSC)}, author={Ghosh, R. and Asha, K.S. and Pratik, S.M. and Datta, A. and Nath, R. and Mandal, S.}, year={2014}, pages={21195–21200} }