Analysis for efficiency potential of high‐efficiency and next‐generation solar cells

This paper overviews photovoltaic R&D projects in Japan. Recently, world-record and second highest efficiencies of various types of solar cells have been demonstrated under the New Energy and Industrial Technology Development Organization Project: 44.4% (under concentration) and 37.9% (under 1 sun) InGaP/GaAs/InGaAs inverted metamorphic 3-junction solar cells by Sharp, 26.7% single crystalline Si heterojunction back-contact solar cell by Kaneka, 22.3% copper indium gallium selenide solar cell by Solar Frontier, a-Si/mu c-Si/mu c-Si thin-film triple-junction solar cell with stabilized efficiency of 14.0% by AIST, 11.9% dye-sensitized solar cell by Sharp, and 11.2% organic solar cell by Toshiba. This paper also presents efficiency potential of high-efficiency and next-generation solar cells analyzed by considering external radiative efficiency, open-circuit voltage loss, and fill factor loss. Efficiency potential of crystalline Si, GaAs, III-V compound 3-junction and 5-junction, CIGSe, CdTe, CZTS(Se), multiquantum well, and quantum dot and perovskite solar cells is shown to be 28.5%, 29.7%, 40%, 43%, 26.5%, 26.5%, 20%, 25.8%, and 24.9% under 1 sun, respectively.