Energy Harvesting for GaAs Photovoltaics Under Low-Flux Indoor Lighting Conditions

• Published in: IEEE transactions on electron devices Vol. 63; no. 7; pp. 2820 - 2825
• Main Authors: Teran, Alan S., Moon, Eunseong, Lim, Wootaek, Kim, Gyouho, Lee, Inhee, Blaauw, David, Phillips, Jamie D.
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.07.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Compound semiconductors; Dark current; Devices; Diodes; Efficiency; electronic devices; Energy conversion efficiency; Energy harvesting; Gallium arsenide; Illumination; Lighting; Photovoltaic cells; Photovoltaic systems; recombination; Resistance; Solar cells; Compound semiconductors; diodes; recombination; electronic devices
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2016.2569079

GaAs photovoltaics are promising candidates for indoor energy harvesting to power small-scale (<inline-formula> <tex-math notation="LaTeX">\approx 1 </tex-math></inline-formula> mm 2 ) electronics. This application has stringent requirements on dark current, recombination, and shunt leakage paths due to low-light conditions and small device dimensions. The power conversion efficiency and the limiting mechanisms in GaAs photovoltaic cells under indoor lighting conditions are studied experimentally. Voltage is limited by generation-recombination dark current attributed to perimeter sidewall surface recombination based on the measurements of variable cell area. Bulk and perimeter recombination coefficients of 1.464 pA/mm 2 and 0.2816 pA/mm, respectively, were extracted from dark current measurements. Resulting power conversion efficiency is strongly dependent on cell area, where current GaAs of 1-mm 2 indoor photovoltaic cells demonstrates power conversion efficiency of approximately 19% at 580 lx of white LED illumination. Reductions in both bulk and perimeter sidewall recombination are required to increase maximum efficiency (while maintaining small cell area near 1 mm 2 ) to approach the theoretical power conversion efficiency of 40% for GaAs cells under typical indoor lighting conditions.