RT Conference Proceedings SR 00 ID 10.1109/PVSC40753.2019.8980563 A1 Zehender, Marius Harry A1 García Vara, Iván A1 Svatek, Simon Aurel A1 Steiner, Myles A. A1 García Linares, Pablo A1 Warren, Emily A1 Tamboli, Adele A1 Martí Vega, Antonio A1 Antolín Fernández, Elisa T1 Demonstrating the GaInP/GaAs three-terminal Heterojunction Bipolar Transistor Solar Cell YR 2019 FD 16/06/2019 - 21/06/2019 SP 35 OP 40 K1 Double junction; multi terminal; independent current; photovoltaic cells; gallium indium phosphide; gallium arsenide AB The three-terminal heterojunction bipolar transistor solar cell (HBTSC) concept enables the realization of a monolithic double-junction device with individual current extraction. We present an HBTSC realized by a heterojunction of GaInP and GaAs. The one-sun open-circuit voltage (V OC ) of the top and bottom junctions are 1.33 V and 0.99 V, respectively, while fill factors (FF) are above 80%. At one-sun illumination, reducing one junction's bias from V OC to maximum power point degrades the performance of the other junction only slightly (<; 0.5% efficiency loss). These results demonstrate the potential of the HBTSC concept to produce high-efficiency independently connected double-junction solar cells. T2 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) ED Chicago, IL, USA AV Published LK https://oa.upm.es/64911/ UL https://ieeexplore.ieee.org/document/8980563