Perovskite‐CIGSe Tandem Solar Cell: Over One Year of Outdoor Monitoring

Tandem solar cells can surpass the limitations of single‐junction devices, promising increased performance due to lower thermalization losses. Even though many research and industrial upscaling efforts are based on perovskite‐Si tandems, all‐thin‐film photovoltaic (PV) devices, for instance with chalcopyrite (CIGSe) and perovskite, can offer many advantages such as significant cost and material savings and access to niche markets like building integrated‐ and flexible PV. However, long‐term stability and outdoor performance of perovskite‐based tandem devices is to this day challenging. This work presents the first data analysis of year‐round outdoor measurements (mpp‐tracked) of a perovskite‐chalcopyrite tandem device with a starting efficiency of about 23.14% before encapsulation. The maximum outdoor performance of the tandem device changed during the period of observation, reaching the peak performance in April and then decreased due to the device degradation. At its maximum outdoor performance, the tandem could reach up to 68% higher instantaneous power output, relative to its single‐junction reference (CIGSe‐SJ). In addition, a quantitative time series performance analysis, exemplary qualitative imaging characterization of the tandem before and after outdoor exposure, is shown. Finally, the possibility of predicting the immediate performance of an all‐thin‐film tandem is verified by using a multiple linear regression model with accuracies generally exceeding 90%.