Organic Solar Cells at Stratospheric Condition for High Altitude Platform Station Application

High specific power or power to mass ratio is a critical concern of photovoltaic (PV) for aerospace applications. Organic solar cells (OSCs) have advantages such as high absorption coefficient, compatibility with flexible substrate, light-weight, etc. Moreover, recently OSCs achieved power conversion efficiency (PCE) over 20% with the incorporation of the non-fullerene based small molecule acceptor and high specific power is believed to be obtained. To enter the market, high-altitude platform station (HAPS) is perhaps the first place to start with. In this work, we explore and compare the in-situ performance of two high performing OSCs, using the same donor but different acceptors, in mimic HAPS environment where the pressure, temperature and the illumination conditions are controlled. We found that the use of acceptor can result in substantial difference in the performance at low temperatures.