@article{zhang_pugliano_cao_kim_annam_popy_pinky_yang_garg_borunda_et al._2023, title={Crystal growth, structural and electronic characterizations of zero-dimensional metal halide (TEP)InBr<sub>4</sub> single crystals for X-ray detection}, volume={11}, ISSN={["2050-7534"]}, DOI={10.1039/d3tc02787b}, abstractNote={Recently, metal halides have shown great potential for applications such as solar energy harvesting, light emission, and ionizing radiation detection. In this work, we report the preparation, structural, thermal, and electronic properties of a new zero-dimensional (0D) halide (TEP)InBr4 (where TEP is tetraethylphosphonium organic cation, C8H20P+). (TEP)InBr4 single crystals are obtained within a few days of continuous crystal growth time via a solution growth methodology. (TEP)InBr4 shows a relatively large optical bandgap energy of 4.32 eV and a low thermal conductivity between 0.33±0.05 and 0.45±0.07 W/m-K. Based on the density functional theory (DFT) calculations, the highest occupied molecular orbitals (HOMOs) of (TEP)InBr4 are dominated by the Br states, while the lowest unoccupied molecular orbitals (LUMOs) are constituted by both In and Br states. (TEP)InBr4 single crystals exhibit a semiconductor resistivity of 1.73×1013 Ω·cm and a mobility-lifetime (mu-tau) product of 2.07×10-5 cm2/V. Finally, a prototype (TEP)InBr4 single crystal-based X-ray detector with a detection sensitivity of 569.85 uCGy-1cm-2 (at electrical field E=100 V/mm) was fabricated, indicating the potential use of (TEP)InBr4 for radiation detection applications.}, number={43}, journal={JOURNAL OF MATERIALS CHEMISTRY C}, author={Zhang, Zheng and Pugliano, Tony M. and Cao, Da and Kim, Doup and Annam, Roshan S. and Popy, Dilruba A. and Pinky, Tamanna and Yang, Ge and Garg, Jivtesh and Borunda, Mario F. and et al.}, year={2023}, month={Nov}, pages={15357–15365} }
 @article{alshogeathri_cao_kim_yang_2023, title={Gel growth and characterization of Cs3Bi2Br9 perovskite single crystals for radiation detection}, volume={11}, ISSN={2296-424X}, url={http://dx.doi.org/10.3389/fphy.2023.1129301}, DOI={10.3389/fphy.2023.1129301}, abstractNote={Metal halide perovskites have been sought for ionizing radiation detection due to their tunable bandgap, high quantum yield, high absorption coefficient, excellent charge transport properties, flexible chemistry synthesis and cost-effective manufacturing. Among the family of perovskites, bismuth-based halide perovskites have attracted a rapidly growing interest as possible alternatives to lead-based halide perovskites in the development of nontoxic perovskites for opto-electronic devices. Herein, bismuth-based inorganic perovskite Cs3Bi2Br9 single crystals were successfully grown using an innovative dual-diffusion gel growth technique for the first time. Silica gel has been developed as an enabling medium for gel growth of single crystals due to its transparency and easy control of nucleation sites. The UV-vis transmission spectrum was recorded using a light source of deuterium and halogen lamps and a Tauc plot was obtained, which gave an estimate of the bandgap energy, 2.54 eV. Silver electrodes were used on the top surface and the bottom surface of Cs3Bi2Br9 single crystals for material characterization and detector tests. Current-voltage (I-V) measurements gave a room-temperature resistivity of 1.79 × 10 11   Ω • c m . The Cs3Bi2Br9 single crystals were then tested for X-ray response using ON\OFF testing which revealed attractive responsiveness for X-ray photons (rise and fall time: ≈ 0.3   s ). Using the net current ( I X r a y − I d a r k ), which can be extracted from the X-ray response measurements at varied applied voltages, a modified Hecht fitting was applied to estimate the mobility-lifetime product of electrons, μ τ = 5.12 × 10 − 4   ± 6.70 × 10 − 5   c m 2 / V for a Ag/Cs3Bi2Br9/Ag device. This study shows that our innovative crystal growth method, enabled by the unique gel growth process, can be used as an appealing technique to grow functional crystals for opto-electronic devices. Meanwhile, Cs3Bi2Br9 has shown great potential as a promising candidate for X-ray detection applications. The efforts in this work will serve as a metric for growing halide perovskites in the gel for opto-electronic devices.}, journal={Frontiers in Physics}, publisher={Frontiers Media SA}, author={Alshogeathri, Saqr and Cao, Da and Kim, Doup and Yang, Ge}, year={2023}, month={Mar} }
 @article{cao_yang_2022, title={Effect of low-temperature annealing on Bi-poor Cs2AgBiBr6 single crystals}, volume={33}, ISSN={["2352-4928"]}, url={http://dx.doi.org/10.1016/j.mtcomm.2022.104242}, DOI={10.1016/j.mtcomm.2022.104242}, abstractNote={All-inorganic double perovskite Cs 2 AgBiBr 6 has attracted increasing research interest due to its great potential for optoelectronic applications. To date, most studies focus on the room-temperature characteristics of as-grown Cs 2 AgBiBr 6 single crystals. In this work, we investigated the effect of low-temperature annealing on the physical properties of Cs 2 AgBiBr 6 single crystals. The studied Cs 2 AgBiBr 6 single crystal was grown using a Bi-poor precursor and has a bandgap of 2.12 eV, showing superior elastic properties with Young’s modulus at 32 GPa and hardness at 1 GPa. When the annealing temperature increased from 25 °C to 80 °C, the resistivity of the as-fabricated Bi-poor Cs 2 AgBiBr 6 crystal decreased from 8.07×10 9 Ω cm to 5.86×10 7 Ω cm. Interestingly, the room-temperature resistivity of the annealed Cs 2 AgBiBr 6 increased nearly 3 times when compared to the original value before the annealing. After the annealing, the Cs 2 AgBiBr 6 crystal still holds a strong response to radiation sources. The temporal response of the Cs 2 AgBiBr 6 crystal under the 568-nm LED illumination also indicated that the rising time and the decay time are much shorter than the initial values before the annealing. These results demonstrate a robust thermal and air stability of Bi-poor Cs 2 AgBiBr 6 single crystal. An effective annealing strategy could play an important role in tuning the fast decay- and rise-time characteristics of Cs 2 AgBiBr 6 single crystals. • Fabricated Bi-poor Cs 2 AgBiBr 6 single crystals and studied the effect of low-temperature annealing on it. • The resistivity increased nearly 3 times after the annealing temperature up to 80 °C. • The fabricated device showed a strong response to gamma sources and LED illumination of 568 nm before and after annealing. • The response time to LED illumination enhanced a lot after low-temperature annealing.}, journal={MATERIALS TODAY COMMUNICATIONS}, publisher={Elsevier BV}, author={Cao, Da and Yang, Ge}, year={2022}, month={Dec} }
 @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={http://www.scopus.com/inward/record.url?eid=2-s2.0-85101826920&partnerID=MN8TOARS}, DOI={10.1002/adom.202001575}, abstractNote={Lead halide perovskites have recently attracted intensive attention as competitive alternative candidates of legacy compound materials CdTe, CdZnTe, and TlBr for high sensitivity energy‐resolving gamma‐ray detection at room temperature. However, the use of lead in these lead halide perovskites, which is necessary for increasing the stopping power of gamma radiation, poses a serious environmental concern due to the high toxicity of lead. In this regard, environmental‐friendly perovskite‐based gamma‐ray detector materials with key energy‐resolving capabilities are highly desired. Here, the gamma energy‐resolving performance of a new class of all‐inorganic and lead‐free Cs2AgBiBr6 double perovskite single crystals (SCs) is reported. Two types of Cs2AgBiBr6 SCs, prepared by Bi‐normal and Bi‐poor precursor solutions, respectively, have been grown. Their mobilities and response to gamma radiation are presented. Density of trap states in Bi‐poor Cs2AgBiBr6 SCs (2.65 × 109 cm−3) is one order of magnitude lower than that in Bi‐normal Cs2AgBiBr6 SCs (3.85 × 1010 cm−3). Using laser‐induced photocurrent measurements, the obtained mobility–lifetime (μ–τ) product in Bi‐poor Cs2AgBiBr6 SCs is 1.47 × 10−3 cm2 V−1, indicating their great potentials for gamma‐ray detection. Further, the fabricated detector based on Bi‐poor Cs2AgBiBr6 SC shows response to 59.5 keV gamma‐ray with an energy resolution of 13.91%.}, 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{cao_yang_bourham_moneghan_2020, title={Gamma radiation shielding properties of poly (methyl methacrylate) / Bi2O3 composites}, volume={52}, ISSN={["1738-5733"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85085064327&partnerID=MN8TOARS}, DOI={10.1016/j.net.2020.04.026}, abstractNote={This work investigated the gamma-ray shielding performance, and the physical and mechanical properties of poly (methyl methacrylate) (PMMA) composites embedded with 0–44.0 wt% bismuth trioxide (Bi2O3) fabricated by the fast ultraviolet (UV) curing method. The results showed that the addition of Bi2O3 had significantly improved the gamma shielding ability of PMMA composites. Mass attenuation coefficient and half-value layer were examined using five gamma sources (Cs-137, Ba-133, Cd-109, Co-57, and Co-60). The high loading of Bi2O3 in the PMMA samples improved the micro-hardness to nearly seven times that of the pure PMMA. With these enhancements, it was demonstrated that PMMA/Bi2O3 composites are promising gamma shielding materials. Furthermore, the fast UV curing exerts its great potential in significantly shortening the production cycle of shielding material to enable rapid manufacturing.}, number={11}, journal={NUCLEAR ENGINEERING AND TECHNOLOGY}, author={Cao, Da and Yang, Ge and Bourham, Mohamed and Moneghan, Dan}, year={2020}, month={Nov}, pages={2613–2619} }
 @article{cao_yang_2020, title={Quantum dot/polymer nanocomposite monolith for radiation detection}, volume={24}, ISSN={["2352-4928"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85085179655&partnerID=MN8TOARS}, DOI={10.1016/j.mtcomm.2020.101246}, abstractNote={Plastic scintillators have received strong interest as an important type of radiation sensing material due to their relatively high light output, fast decay time, low fabrication cost, excellent durability, and most importantly, the capability to be shaped into desired forms through the use of molds or other approaches. However, the interior sensitivity and energy resolution of traditional plastic scintillators limit their competitiveness when compared with their inorganic counterparts. The doping of quantum dots (QDs) with high-Z element into plastic scintillators has recently been demonstrated as an effective way to improve gamma stopping power and scintillation efficiency. In this regard, a series of research activities have been conducted to address the aggregation and self-absorption problem of QDs to achieve high-performance transparent plastic scintillators with a high concentration of QDs load. Here we present a comprehensive review to offer a timely reference source to accelerate the development of this exciting research area. This review covers the description of basic theory, the summary of recent experimental progress, and the discussion of future trends of QD-doped nanocomposite plastic scintillators.}, journal={MATERIALS TODAY COMMUNICATIONS}, author={Cao, Da and Yang, Ge}, year={2020}, month={Sep} }
 @article{shen_wu_cao_wang_hu_2019, title={Effect of Ag nanoclusters deposited with magnetron sputtering on laser-induced breakdown spectroscopy enhancement}, volume={156}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85065176461&partnerID=MN8TOARS}, DOI={10.1016/j.sab.2019.05.001}, abstractNote={In this paper, we report experimental observation of the influence of Ag nanoclusters growth on nanoparticle enhanced laser-induced breakdown spectroscopy (NELIBS). In this work, we studied changes in the emission intensity of LIBS, on the example of Si I line at the wavelength of 390.55 nm, as a function of the silver nanoclusters coverage. The emission intensity initially increases before beginning to saturate, and then decreases with increasing Ag nanoclusters coverage. The obtained Ag clusters show a red-shifted plasmon resonance peak with increasing cluster coverage. Atomic force microscopy (AFM) was used to provide information changes in the cluster size and shape. Additionally, a 3D finite-difference-time-domain (FDTD) simulation was performed to estimate the electric field enhancement numerically.}, journal={Spectrochimica Acta - Part B Atomic Spectroscopy}, author={Shen, J. and Wu, K. and Cao, D. and Wang, J. and Hu, B.}, year={2019}, pages={59–65} }
 @article{wu_shen_cao_cheng_sun_hu_2018, title={Coulombic Effect of Amphiphiles with Metal Nanoparticles on Laser-Induced Breakdown Spectroscopy Enhancement}, volume={122}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85052289654&partnerID=MN8TOARS}, DOI={10.1021/acs.jpcc.8b03008}, abstractNote={In this paper, an experimental evidence of enhanced laser-induced breakdown spectroscopy (LIBS) emission using nanoparticles and amphiphiles was reported. The measurement showed an enhanced emission from the K-I lines at the wavelengths of 766.5 and 769.9 nm when the cationic amphiphile of hexadecyl trimethyl ammonium bromide was adsorbed on Au NPs, but no LIBS signal was observed for the anionic amphiphile of sodium dodecyl sulfate or for Au NPs alone. This significant enhancement can be attributed to Coulombic force of attraction between the cationic amphiphile and negatively charged Au NPs and hence the enhanced electric field due to the existence of Au NPs. The detection limit for potassium was shown to be 13 ppb. The new technique provides an effective method for the improvement of the detection sensitivity of LIBS.}, number={33}, journal={Journal of Physical Chemistry C}, author={Wu, K. and Shen, J. and Cao, D. and Cheng, H. and Sun, S. and Hu, B.}, year={2018}, pages={19133–19138} }