2D Surface Passivation in Semi-transparent Perovskite Top Solar Cells with Engineered Bandgap for Tandem Photovoltaics

Wide-bandgap perovskite top solar cells (PSCs) with optimal bandgap (Eg) are key to boost the efficiency of perovskite/Si tandem devices beyond the Shockley-Queisser limit for single-junction solar cells. However, the large open circuit voltage (Voc) deficit in the optimal bandgap range and the poor transmission of the top semi-transparent perovskite solar cells (s-PSCs) restricts the development in this field. Here, we present a novel 2D/3D perovskite heterostructure architecture to reduce the voltage deficit in PSCs. The reduced voltage deficit is a result of the decreased non-radiative recombination losses at the perovskite/hole-transport layer interface. Employing the 2D/3D perovskite heterostructure, efficient four-terminal (4T) perovskite/Si tandem solar cells with a stabilized power conversion efficiency (PCE) of up to 25.7% is demonstrated. In order to improve the PCE further, we present alternative transparent conductive oxide electrodes that reduce the parasitic absorption and reflection losses and enhances the transmission in the near infrared wavelengths, leading to a potential PCE of 27.4% for 4T perovskite/c-Si tandem devices.