Event Date: 07 Jul 2015 01:30 AM - 07 Jul 2015 02:30 AM

Event Venue: Tower Building, Level 2, CREATE Seminar Room

SinBeRISE Seminar Series

A direct thin-film path towards low-cost large-area III-V photovoltaics and optoelectronics

By Prof Ali Javey

Seminar Abstract:
III-V photovoltaics (PVs) have demonstrated the highest power conversion efficiencies for both single- and multi-junction cells. However, expensive epitaxial growth substrates, low precursor utilization rates, long growth times, and large equipment investments restrict applications to concentrated and space photovoltaics (PVs). In this talk, I will discuss our recent work on the vapor-liquid-solid (VLS) growth of high-quality III-V thin-films on metal foils as a promising platform for large-area terrestrial PVs overcoming the above obstacles. We have demonstrated growth of 1-3 m thick InP thin-films on non-epitaxial substrates with ultra-large grain size up to 1mm, which is ~1000 times larger than those obtained by conventional vapor-solid growth processes. The films exhibit electron mobilities as high as 500 cm2/V-s and minority carrier lifetimes as long as 80 ns. Furthermore, under 1-sun equivalent illumination, photoluminescence efficiency measurements indicate that an open circuit voltage of up to 930 mV can be achieved with our films, only 40 mV lower than what we measure on a single crystal reference wafer. The work presents a new pathway for low-cost III-V solar cells with high efficiencies. In addition, I will present our progress on forming doping-free, selective electron and hole contacts to single crystalline silicon with the goal of achieving high efficiency Si cells, free of doped junctions. Finally, I will present an update on Bay Area PV Consortium, co-led by UC Berkeley and Stanford, as a model academic research center with strong industrial partnership to fuel transfer of knowledge from universities to industry.