@article{popy_creason_zhang_singh_saparov_2022, title={Electronic structures and optical properties of (Ph4P)MX2 (M = Cu, Ag; X = Cl, Br)}, url={https://doi.org/10.1016/j.jssc.2022.123626}, DOI={10.1016/j.jssc.2022.123626}, abstractNote={In recent years, all inorganic copper(I) halides have emerged as an exciting new class of optical materials that demonstrate high-efficiency photoluminescence (PL) properties. Here, we report the synthesis and characterization of a series of hybrid copper(I) and silver(I) halides (Ph4P)MX2 (M ​= ​Cu, Ag; X ​= ​Cl, Br) containing tetraphenylphosphonium (Ph4P+) cation as the organic component. Addressing one of the shortcomings of all-inorganic copper(I) halides, inclusion of the bulky organic Ph4P+ cation improves the stability of the hybrid compounds; (Ph4P)MX2 show no sign of degradation upon long-term ambient air exposure. The compounds are found to exhibit unusually weak light emission properties for Cu(I) and Ag(I) halides. Our combined experimental and density-functional theory (DFT) studies attribute the contrasting optical properties of these compounds to their unique crystal and electronic structures. This work provides new materials design perspectives to explore low cost and low toxicity metal halides for light emission applications.}, journal={Journal of Solid State Chemistry}, author={Popy, Dilruba A. and Creason, Tielyr D. and Zhang, Zheng and Singh, David J. and Saparov, Bayram}, year={2022}, month={Dec} }
 @article{zhang_fattal_creason_amiri_roseborough_gilley_nyman_saparov_2022, title={Investigation of the Solution Chemistry of Hybrid Organic–Inorganic Indium Halides for New Material Discovery}, volume={61}, url={http://dx.doi.org/10.1021/acs.inorgchem.2c01161}, DOI={10.1021/acs.inorgchem.2c01161}, abstractNote={Recently, metal halide perovskites (MHPs) have emerged as a new class of materials for optical and electronic applications such as solar cells and ionizing radiation detectors. Although the solution-processability of MHPs is among their greatest advantages, the solution chemistries of most metal halide systems and their relationship with the observed structural and chemical diversity are poorly understood. In this work, we study the solution chemistry of a model indium halide system, methylammonium (MA)-In-Br, using a combination of the UV-vis spectroscopy, electrospray ionization mass spectrometry (ESI-MS) measurements, small-angle X-ray scattering (SAXS), and density functional theory (DFT) calculations. Our results show that indium could form either octahedral [InBr63-] or tetrahedral [InBr4-] anions in solution or a combination of both, depending on the loading ratios of MABr and InBr3 reactants. Understanding the solution chemistry of this system and recognizing the optical fingerprints of these polyanions allow for targeted crystallization of two novel compounds: MAInBr4 featuring tetrahedral [InBr4-] anions and MA2InBr5 containing both octahedral [InBr63-] and tetrahedral [InBr4-] anions. Further increase of the MABr content leads to the formation of previously reported MA4InBr7, containing only octahedral [InBr63-] anions separated by Br- anions. Our results suggest that understanding the solution chemistry of multinary metal halide systems could be a valuable tool for discovering functional materials for practical applications.}, number={33}, journal={Inorganic Chemistry}, publisher={American Chemical Society (ACS)}, author={Zhang, Zheng and Fattal, Hadiah and Creason, Tielyr D. and Amiri, Mehran and Roseborough, Alexander and Gilley, Isaiah W. and Nyman, May and Saparov, Bayram}, year={2022}, month={Aug}, pages={13015–13021} }
 @article{mcwhorter_zhang_creason_thomas_du_saparov_2021, title={(C7H11N2)2MBr4 (M = Cu, Zn): X‐Ray Sensitive 0D Hybrid Metal Halides with Tunable Broadband Emission}, volume={12}, url={http://dx.doi.org/10.1002/ejic.202100954}, DOI={10.1002/ejic.202100954}, abstractNote={Abstract}, journal={European Journal of Inorganic Chemistry}, publisher={Wiley}, author={McWhorter, Timothy M and Zhang, Zheng and Creason, Tielyr D and Thomas, Leonard M and Du, Mao-Hua and Saparov, Bayram}, year={2021}, month={Dec} }
 @article{zhang_saparov_2021, title={Charge carrier mobility of halide perovskite single crystals for ionizing radiation detection}, url={https://doi.org/10.1063/5.0057411}, DOI={10.1063/5.0057411}, abstractNote={Halide perovskites have recently emerged as promising semiconductor materials for several applications including solar cells, light-emitting diodes, and radiation detectors. The charge carrier transport properties, which could be evaluated by the mobility-lifetime (mu-tau or μ-г) product, serve an important role for the development of halide perovskites for radiation detection applications. In this Perspective, we first explain the charge transport mechanism and the limiting factors that determine the intrinsic charge carrier mobility in halide perovskite single crystals. Then, we overview the techniques and methods that have been employed for evaluating the charge carrier mobility (for both electrons and holes). Finally, we discuss the discrepancy in the experimentally determined carrier mobility from the literature for halide perovskite single crystals, and provide a perspective on future developments for carrier mobility enhancement.}, journal={Applied Physics Letters}, author={Zhang, Zheng and Saparov, Bayram}, year={2021}, month={Jul} }
 @article{zhang_cao_huang_danilov_chung_sun_yang_2021, title={Gamma-Ray Detection Using Bi-Poor Cs2AgBiBr6 Double Perovskite Single Crystals}, volume={9}, ISSN={["2195-1071"]}, url={https://doi.org/10.1002/adom.202001575}, DOI={10.1002/adom.202001575}, abstractNote={Abstract}, number={8}, journal={ADVANCED OPTICAL MATERIALS}, publisher={Wiley}, author={Zhang, Zheng and Cao, Da and Huang, Zhengjie and Danilov, Evgeny O. and Chung, Ching-Chang and Sun, Dali and Yang, Ge}, year={2021}, month={Apr} }
 @article{zhang_bader_lucia_yang_2021, title={Improved stress relaxation resistance of composites films by soy protein polymer}, volume={24}, ISSN={["2452-2139"]}, DOI={10.1016/j.coco.2021.100644}, abstractNote={Stress relaxation is an important parameter factor to determine the applicability of materials under the condition of dynamic loading. We found that soy protein polymer (SPP), a natural polymer, can improve stress relaxation resistance of polyvinyl alcohol (PVOH) films. Such improvement in stress relaxation resistance was accompanied by improved thermal stability. A mechanism of the improved stress relaxation resistance was proposed and was attributed to constructive interactions between SPP and PVOH, which restricted motions and rearrangements of polymeric chains. Such hypothesis was supported by differential scanning calorimetry (DSC) and modeling results in which decreased crystallizability and increased relaxation time for the composites systems were observed.}, journal={COMPOSITES COMMUNICATIONS}, author={Zhang, Zhen and Bader, Yousef M. Katba and Lucia, Lucian A. and Yang, Jianzhong}, year={2021}, month={Apr} }
 @article{zhang_ma_thomas_gofryk_saparov_2021, title={Physical Properties of Candidate X-ray Detector Material Rb4Ag2BiBr9}, volume={12}, url={http://dx.doi.org/10.1021/acs.cgd.1c00986}, DOI={10.1021/acs.cgd.1c00986}, abstractNote={Recently, metal halide perovskites have emerged as promising semiconductor candidates for sensitive X-ray photon detection due to their suitable bandgap energies, excellent charge transport properties, and low material cost afforded by their low-temperature solution-processing preparation. Here, we report an improved methodology for single crystal (SC) growth, thermal and electrical properties of a two-dimensional (2D) layered halide material Rb4Ag2BiBr9, which has been identified as a potential candidate for X-ray radiation detection applications. The measured heat capacity for Rb4Ag2BiBr9 implies that there are no structural phase transitions upon cooling. Temperature dependence of thermal transport measurements further suggest remarkably low thermal conductivities of Rb4Ag2BiBr9 that are comparable to the lowest reported in literature. The bulk crystal resistivity is determined to be 2.59×109 Ω·cm from the current-voltage (I-V) curve. Density of trap states are estimated to be ~1010 cm-3 using the space-charge-limited-current (SCLC) measurements. The fabricated Rb4Ag2BiBr9-based X-ray detector shows good operational stability with no apparent current drift, which may be ascribed to the 2D crystal structure of Rb4Ag2BiBr9. Finally, by varying the X-ray tube current to change the corresponding dose rate, the Rb4Ag2BiBr9 X-ray detector sensitivity is determined to be 222.03 uCGy-1cm-2 (at an electric field of E = 24 V/mm).}, journal={Crystal Growth & Design}, publisher={American Chemical Society (ACS)}, author={Zhang, Zheng and Ma, Ying-Zhong and Thomas, Leonard and Gofryk, Krzysztof and Saparov, Bayram}, year={2021}, month={Dec} }
 @misc{zhang_yang_2021, title={Recent advancements in using perovskite single crystals for gamma-ray detection}, volume={32}, ISSN={["1573-482X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85085091410&partnerID=MN8TOARS}, DOI={10.1007/s10854-020-03519-z}, number={10}, journal={JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS}, author={Zhang, Zheng and Yang, Ge}, year={2021}, month={May}, pages={12758–12770} }
 @article{zhang_chung_huang_vetter_seyitliyev_sun_gundogdu_castellano_danilov_yang_2020, title={Towards radiation detection using Cs2AgBiBr6 double perovskite single crystals}, volume={269}, ISSN={0167-577X}, url={http://dx.doi.org/10.1016/j.matlet.2020.127667}, DOI={10.1016/j.matlet.2020.127667}, abstractNote={In this work, we studied the optical- and electrical- properties of emerging Cs2AgBiBr6 double perovskite single crystals and demonstrated their potential for detecting ionizing radiation. We prepared Cs2AgBiBr6 double perovskite single crystals from a saturated aqueous solution. Low-temperature photoluminescence (PL) was employed to determine the bandgap energies of Cs2AgBiBr6, which are 2.00 eV (indirect) and 2.26 eV (direct) respectively. Using the space charge limited current method, we estimated the density of trap states and mobility of charge carriers as 1.44 × 1010 cm−3 and 7.02 cm2/V-s respectively. A lower bound value of the mobility-lifetime (μ-τ) product of 2.48 × 10−3 cm2/V was determined using 450 nm laser excitation, which was sufficient for ensuring a long drift distance of charge carriers for several radiation detector applications. Furthermore, we tested the direct response of Cs2AgBiBr6 single crystals to X-ray radiation. Our Cs2AgBiBr6 single crystal device with gold electrodes deposited on the two parallel surfaces exhibited excellent linear response to low energy X-rays.}, journal={Materials Letters}, publisher={Elsevier BV}, author={Zhang, Zheng and Chung, Ching-Chang and Huang, Zhengjie and Vetter, Eric and Seyitliyev, Dovletgeldi and Sun, Dali and Gundogdu, Kenan and Castellano, Felix N. and Danilov, Evgeny O. and Yang, Ge}, year={2020}, month={Jun}, pages={127667} }
 @article{zhang_yang_zhou_chung_hany_2019, title={Optical and electrical properties of all-inorganic Cs2AgBiBr6 double perovskite single crystals}, volume={9}, ISSN={["2046-2069"]}, url={https://doi.org/10.1039/C9RA04045E}, DOI={10.1039/C9RA04045E}, abstractNote={Temperature-dependent resistivity and cathodoluminescence (CL) measurements of solution-processed Cs2AgBiBr6 double perovskite single crystals.}, number={41}, journal={RSC ADVANCES}, publisher={Royal Society of Chemistry (RSC)}, author={Zhang, Zheng and Yang, Ge and Zhou, Chuanzhen and Chung, Ching-Chang and Hany, Ibrahim}, year={2019}, month={Aug}, pages={23459–23464} }