A5002993046- Chalcogenide Semiconductor Thin Films
- Quantum Dots Synthesis And Properties
- Copper-based nanomaterials and applications
- Semiconductor materials and interfaces
- Perovskite Materials and Applications
- Advanced Semiconductor Detectors and Materials
- Machine Learning in Materials Science
- Solid-state spectroscopy and crystallography
- Optical properties and cooling technologies in crystalline materials
- Electron and X-Ray Spectroscopy Techniques
- Crystal Structures and Properties
- Magneto-Optical Properties and Applications
- MXene and MAX Phase Materials
- Magnetic Properties and Synthesis of Ferrites
- 2D Materials and Applications
- Electronic and Structural Properties of Oxides
- Solar Thermal and Photovoltaic Systems
- Advancements in Photolithography Techniques
- Iron-based superconductors research
- Iron oxide chemistry and applications
- Semiconductor materials and devices
- Inorganic Chemistry and Materials
- Industrial Vision Systems and Defect Detection
University of Florida
2019-2025
Drexel University
2023
National Renewable Energy Laboratory
2023
University of Luxembourg
2023
Helmholtz-Zentrum Berlin für Materialien und Energie
2016-2020
Purdue University West Lafayette
2012-2016
We introduce new hole-selective contacts for next-generation perovskite photovoltaics and point to design paths molecular engineering of perfect interfaces.
Abstract Thin‐film solar cells using Cu 2 ZnSn(S,Se) 4 absorber materials continue to attract increasing attention. The synthesis of kesterite ZnSnS nanoparticles by a modified method hot injection is explained. Characterization the energy dispersive X‐ray spectroscopy, diffraction, Raman, and transmission electron microscopy presented discussed. When suspended in an ink, coated, processed into device, obtained this achieve total area (active area) efficiency 9.0% (9.8%) AM 1.5 illumination...
Abstract Nanocrystal‐based Cu 2 Zn(Sn y Ge 1‐y )(S x Se 4‐x ) (CZTGeSSe) thin‐film solar cell absorbers with tunable band gap have been prepared. Maximum solar‐conversion total area efficiencies of up to 9.4% are achieved a content 30 at.%. Improved performance compared similarly processed films ZnSn(S (CZTSSe, 8.4% efficiency) is through controlling loss from the bulk absorber film during high‐temperature selenization treatment, although some surface still observed following this step....
Abstract The performance of many emerging compound semiconductors for thin‐film solar cells is considerably lower than the Shockley–Queisser limit, and one main reasons this presence various deleterious defects. A partial or complete substitution cations presents a viable strategy to alter characteristics detrimental defects defect clusters. Particularly, it hypothesized that double cation could be feasible mitigate negative effects different types In study, on pure‐sulfide Cu 2 ZnSnS 4...
Abstract The structural phases and optoelectronic properties of coevaporated CsPbI 3 thin films with a wide range [CsI]/[PbI 2 ] compositional ratios are investigated using high throughput experimentation gradient samples. It is found that for CsI‐rich growth conditions, can be synthesized directly at low temperature into the distorted perovskite γ‐CsPbI phase without detectable secondary phases. In contrast, PbI ‐rich conditions to lead non‐perovskite δ‐phase. Photoluminescence spectroscopy...
Time‐resolved photoluminescence (TRPL) is a powerful characterization technique to study carrier dynamics and quantify absorber quality in semiconductors. The minority lifetime, which critically important for high‐performance solar cells, often derived from TRPL analysis. However, here it shown that various nonideal properties can dominate the signal making reliable extraction of lifetime not possible. Through high‐resolution intensity‐, temperature‐, voltage‐dependent, spectrally resolved...
Abstract We report a total‐area power conversion efficiency of 15% for copper indium gallium disulfoselenide (CIGSSe) solar cell fabricated from disulfide (CIGS) nanoparticle ink based process. Careful optimization the fabrication process has resulted in significant improvement compared to our previously reported 12%. This ranks among highest literature solution processed CIGSSe. Despite having an absorber thickness approximately 700–800 nm, which is less than half high devices grown by both...
Abstract The performance‐boosting effect of alkali treatments is well known for chalcogenide thin‐film solar cells based on Cu(In,Ga)Se 2 (CIGS) and Cu ZnSn(S,Se) 4 (CZTSSe–kesterite) absorbers. In contrast to heavier elements, lithium expected alloy with the kesterite phase leading solid solution (Li x 1− ) (LCZTSSe), which offers a way tuning semiconductor bandgap by changing ratio Li/(Li+Cu). Here presented an experimental series solution‐processed LCZTSSe fraction Li/(Li+Cu) ranging from...
Detailed quantum efficiency (QE) analysis of a nanoparticle-based Cu2ZnSnSe4 (CZTSe) solar cell has been conducted to understand photogenerated carrier collection in the device. Specifically, voltage-dependent considered characterize both diffusion limitations and recombination collection. Application generalized QE model corresponding experimental analytical procedures are presented account for non-ideal device behavior, with specific consideration charge trapping, finite absorber...
Large-grain absorber formation through selenization techniques is a promising route for high performance chalcogenide solar cells. Understanding and subsequently controlling such grain growth essential in improving quality developing absorbers with unique optoelectronic morphological properties. We explain the role of liquid selenium Cu2ZnSnSe4 (CZTSe) from Cu2ZnSnS4 nanoparticles by proposing liquid-assisted mechanism. Through use multizone rapid-thermal-processing furnace, control Se...
Abstract The identification of performance‐limiting factors is a crucial step in the development solar cell technologies. Cu 2 ZnSn(S,Se) 4 ‐based cells have shown promising power conversion efficiencies recent years, but their performance remains inferior compared to other thin‐film cells. Moreover, fundamental material characteristics that contribute this are unclear. In paper, role deep‐trap‐level‐inducing 2Cu Zn +Sn defect clusters revealed by comparing formation energies and...
Chalcogenide perovskites constitute a promising earth-abundant, non-toxic, and robust semiconductor family with the potential to compete hybrid as high-quality photovoltaic absorbers. However, low-temperature, solution-based synthesis route has eluded researchers in this area. Here we report colloidal of chalcogenide perovskite BaZrS3 nanoparticles at 330 °C organic solvent. The (10-20 nm) are found be comprised smaller (3-5 crystalline domains. Promising optoelectronic properties for...
Detailed electrical characterization of nanoparticle based Cu2ZnSn(SxSe1−x)4 (CZTSSe) and Cu2Zn(SnyGe1−y)(SxSe1−x)4 (CZTGeSSe) solar cells has been conducted to understand the origin device limitations in this material system. Specifically, temperature dependent current-voltage analysis considered, with particular application non-ideal behavior. Due presence such behavior, typical techniques—commonly applied kesterite-type cells—are found be insufficient performance limitations, an...
Abstract Kesterite Cu 2 ZnSn(S x Se 1- ) 4 (CZTSSe) semiconductor materials have been extensively studied over the past decade, however despite significant efforts, open circuit voltage remains below 60% of theoretical maximum. Understanding optical and electrical properties is critical to explaining solving deficit. This review aims summarize present knowledge kesterites specifically focuses on experimental data intrinsic defects, charge carrier density transport, minority lifetime related...
Chalcogenide perovskites have attracted increasing research attention in recent years due to their promise of unique optoelectronic properties combined with stability. However, the synthesis and processing these materials has been constrained by need for high temperatures and/or long reaction times. In this work, we address open question a low-temperature growth mechanism BaZrS3. Ultimately, liquid-assisted BaZrS3 using molten BaS3 as flux is demonstrated at ≥540 °C little 5 min. The role...
The selenization of metallic Cu–Zn–Sn–Ge precursors is a promising route for the fabrication low-cost and efficient kesterite thin-film solar cells. Nowadays, efficiencies cells are still below 13%. For Cu(In,Ga)Se2 cells, formation compositional gradients along depth absorber layer has been demonstrated to be key requirement producing with conversion above 22% level. No clear understanding reached so far about how produce these in an manner compounds, but among possible candidates, Ge...
Wurtzite-derived copper–zinc–tin sulfide nanoparticle films were observed to undergo a phase transformation kesterite when exposed Se vapor at 500 °C. The resulting dense and selenized Cu2ZnSn(S,Se)4 (CZTSSe) found have the same bilayer structure as absorber layers derived directly from Cu2ZnSnS4 (CZTS) nanoparticles (Guo, Q.; Ford, G. M.; Yang, W.-C.; Walker, B. C.; Stach, E. A.; Hillhouse, H. W.; Agrawal, R. J. Am. Chem. Soc. 2010, 132, 17384−17386). top layer was fully sintered into...
Cu2ZnSn(S,Se)4 (CZTSSe) solar cells typically exhibit high short-circuit current density (Jsc), but have reduced cell efficiencies relative to other thin film technologies due a deficit in the open-circuit voltage (Voc), which prevent these devices from becoming commercially competitive. Recent research has attributed low Voc CZTSSe small scale disorder that creates band tail states within absorber gap, physical processes responsible for this reduction not been elucidated. In paper, we show...
Abstract The mobilities of electrons and holes determine the applicability any semiconductor, but their individual measurement remains a major challenge. Here, we show that time-resolved terahertz spectroscopy (TRTS) can distinguish minority majority charge carriers independently doping-type without electrical contacts. To this end, combine well-established determination sum electron hole from photo-induced THz absorption spectra with mobility-dependent ambipolar modeling TRTS transients....
Recent reports have suggested that the long decay times in time resolved photoluminescence (TRPL), often measured Cu(In, Ga)Se2 absorbers, may be a result of detrapping from sub-bandgap defects. In this work, we show via temperature dependent measurements, lifetimes >50 ns can observed reflect true minority carrier lifetime not related to deep trapping. Temperature and steady state imaging measurements are used analyze effect annealing air nitrogen atmosphere between 300 K 350 K. We...