| AVS 64th International Symposium & Exhibition | |
| Thin Films Division | Thursday Sessions |
| Session TF-ThP |
| Session: | Thin Films Poster Session |
| Presenter: | Devendra Khatiwada, University of Houston |
| Authors: | D. Khatiwada, University of Houston P. Dutta, University of Houston M. Rathi, University of Houston S. Sun, University of Houston Y. Yao, University of Houston Y. Gao, University of Houston Y. Li, University of Houston S. Pouladi, University of Houston J.-H. Ryou, University of Houston V. Selvamanickam, University of Houston |
| Correspondent: | Click to Email |
There is great interest in thin film solar cells for manufacturing cost-effective photovoltaics due to their advantages of light weight, versatile application, mechanical flexibility and scalable length. Thin film solar cells made of III-V semiconductor materials that have a high absorption coefficient over a wide range of the solar spectrum are strong candidates but have been largely unexplored so far. GaAs has high mobility, high band gap and high absorption coefficient and AlGaAs can be lattice matched with GaAs to form a heterojunction structure. While the highest efficiencies have been reported in III-V solar cells based on GaAs and Ge wafers, their application has been very limited due to high cost of these wafers.
Herein, we have developed high quality epitaxial semiconductor thin films on low-cost flexible metal tapes to overcome the wafer cost as well as benefit from the lower manufacturing cost of roll-to-roll processing. In our process, single-crystalline-like germanium films are grown on the flexible metal tape over which epitaxial (Al)GaAs semiconductor thin films are grown by metal organic chemical vapor deposition (MOCVD). The grown device architecture is further processed for contact deposition via photolithography.
The fabricated thin film III-V solar cells exhibit photon conversion efficiency of 7% with open circuit voltage (VOC) of 565mV, short circuit current density (JSC) of 17.9 mA/cm2 and fill factor (FF) of 67% under A.M 1.5 (1 sun). Conversion efficiencies up to 11% have also been demonstrated with the thin film III-V solar cells. Further improvement in device efficiency is being pursued with new device architectures and optimization of the growth and fabrication processes.
This work was partially funded by the U.S. Department of Energy Sunshot Initiative.