EFFECT OF CONCENTRATED SUNLIGHT ON STABILITY OF PEROVSKITE SOLAR CELLS

Perovskite solar cells exhibited certified power conversion efficiency (PCE) which already approached 22%, but to be considered for large scale commercial applications these cells have to be stable under operating conditions like exposure to sunlight, heat and electric bias. Here we present stability studies using concentrated sunlight, which allows rapid screening of the parameters and degradation phenomena present in the cells. Accelerated degradation studies for different bias conditions (open circuit (OC) and short circuit (SC)) under various sunlight intensities were compared with the results of 1 sun exposure in indoor and outdoor stability tests. UV filters were used to find out which part of the solar spectrum causes observed degradation.

Our results on perovskite solar cells with a structure of ITO/SnO₂/Cs_0.15(CH(NH₂)₂)_0.85PbI_2.75Br_0.25/Spiro-OMeTAD/Au showed that faster degradation is found for cells held at SC under concentrated sunlight and on the initial stage of outdoor exposure. However, cells kept at SC showed better long-term stability compared to cells kept at OC upon real operational conditions. We found that the degraded cells can slowly recover to their initial PCE after a long dark storage. Experiments conducted with UV filters revealed that UV light is not the main source of degradation of the cells.