< BK21 플러스 BEST 정보기술 사업단 세미나 개최 안내 >

개최일시 : 2017년 06월 23일 금요일 16:00 ~ 17:00

개최장소 : 제 4공학관 D403호

세미나 제목 : New Approaches for III-V Photovoltaic and Photoelectrochemical Solar Energy Conversion

발표초록 :

Due to their highly favorable materials properties such as direct bandgap, appropriate bandgap energy against solar spectrum, and high electron mobilities, epitaxially grown III-V compound semiconductors have provided unmatched performance in solar energy harvesting. However, their large-scale deployment in terrestrial photovoltaics and solar fuel generation remains as a daunting challenge mainly due to the prohibitively high cost of growing device-quality epitaxial materials. In this regard, unconventional ways to exploit III-V compound semiconductors can create novel engineering designs, device functionalities, and cost structures, each with significant values in the next generation solar energy conversion technologies. In the first part of my talk, I will provide an overview of recent advances in materials design and fabrication concepts towards cost-efficient III-V photovoltaic systems based on multilayer-grown, ultrathin, nanostructured GaAs solar cells.1-2 Ultrathin (emitter + base: 300 nm) microscale solar cells epitaxially grown in triple-stack releasable assemblies exhibited uniform (<3% relative) interlayer photovoltaic performance and contact properties owing to the suppressed diffusion of p-type dopant (beryllium) and reduced time of epitaxial growth in conjunction with ultrathin device configuration. Hexagonally periodic TiO2 nanoposts directly implemented on the window layer served as a lossless diffractive coating for antireflection, diffraction, and light trapping in conjunction with a co-integrated back-surface metal reflectors, providing 20.8% one-sun efficiency with solar cells that have the thickness of active layer more than 10 times thinner than conventional devices. In the second part, I will present a novel strategy for III-V photocatalysis in solar-driven photoelectrochemical water splitting.3 A thin film stack of GaAs-based epitaxial materials was printed onto a non-native transparent substrate to form an integrated photocatalytic electrode for solar hydrogen generation. The heterogeneously integrated bifacial electrode configuration together with specialized epitaxial design strategically decouple materials interfaces for illumination and electrocatalysis, and therefore allow independent control and optimization of light absorption, carrier transport, charge transfer, and materials stability. These advantages synergistically contribute to the high efficiency (~13.1% STH), long lifetime (~ 8 days) operation of unassisted-mode water splitting using a series-connected wireless tandem system of GaAs photoelectrodes.

강연자 Jongseung Yoon, Assistant Professor / Department of Chemical Engineering and Materials Science Viterbi School of Engineering University of Southern California

초청자 : 전기전자공학과 교수 안종현