As we move towards the commercialization and upscaling of perovskite solar cells, it is essential to fabricate them in ambient environment rather than in the conventional glove box environment. The efficiency of ambient-processed perovskite solar cells lags behind those fabricated in controlled environments, primarily owing to external environmental factors such as humidity and temperature. In the case of device fabrication in ambient environments, relying solely on a single parameter, such as temperature or humidity, is insufficient for accurately characterizing environmental conditions. Therefore, the dew point is introduced as a parameter which accounts for both temperature and humidity. In this study, a machine learning model was developed to predict the efficiency of ambient-processed perovskite solar cells based on meteorological data, particularly the dew point. A total of 238 perovskite solar cells were fabricated, and their photovoltaic parameters and dew points were collected from March to December 2023. The collected data were used to train various tree-based machine learning models, with the random forest model achieving the highest accuracy. The efficiencies of the perovskite solar cells fabricated in January and February 2024 were predicted with a MAPE of 4.44%. An additional Shapley Additive exPlanations analysis confirmed the significance of the dew point in the performance of perovskite solar cells.

Monolithic perovskite–silicon tandem solar cells with MoO_x hole selective contact silicon bottom solar cells show a power conversion efficiency of 8%. A thin 15 nm-thick MoO_x contact to n-type Si was used instead of a standard p⁺ emitter to collect holes and the SiO_x/n⁺ poly-Si structure was deposited on the other side of the device for direct tunneling of electrons and this silicon bottom cell structure shows ~15% of power conversion efficiency. With this bottom carrier selective silicon cell, tin oxide, and subsequent perovskite structure were deposited to fabricate monolithic tandem solar cells. Monolithic tandem structure without ITO interlayer was also compared to confirm the role of MoO_x in tandem cells and this tandem structure shows the power conversion efficiency of 3.3%. This research has confirmed that the MoO_x layer simultaneously acts as a passivation layer and a hole collecting layer in this tandem structure.

Tunnel oxide passivated contact (TOPCon) solar cells are key emerging devices in the commercial silicon-solar-cell sector. It is essential to have a suitable bottom cell in perovskite/silicon tandem solar cells for commercial use, given that good candidates boost efficiency through increased voltage. This is due to low recombination loss through the use of polysilicon and tunneling oxides. Here, a thin amorphous silicon layer is proposed to reduce parasitic absorption in the near-infrared region (NIR) in TOPCon solar cells, when used as the bottom cell of a tandem solar-cell system. Lifetime measurements and optical microscopy (OM) revealed that modifying both the timing and temperature of the annealing step to crystalize amorphous silicon to polysilicon can improve solar cell performance. For tandem cell applications, absorption in the NIR was compared using a semitransparent perovskite cell as a filter. Taken together, we confirmed the positive results of thin poly-Si, and expect that this will improve the application of perovskite/silicon tandem solar cells.