Improved Performances of CsPbBr3 Perovskite Solar Cells via PbI2 Additive

The emergence of CsPbBr3 perovskite solar cells (PSCs) with a band gap of approximately 2.3 eV has generated increasing interest stemming from their potential for high open-circuit voltage (Voc), making them particularly suitable for use in tandem configurations or spectral splitting. However, the Voc of PSCs currently falls short of its theoretical limit, driven by trap-mediated charge recombination and energy band alignment mismatch. In this study, we present a straightforward additive engineering approach involving the introduction of PbI2 species into the PbBr2 precursor film to form the I–Pb–Br interaction, retarding the rapid reaction between PbBr2 and CsBr. This approach effectively suppresses the Pb-rich phase CsPb2Br5, eliminates pinholes on the CsPbBr3 crystal, and obtains high-quality perovskite films, which can significantly enhance the photovoltaic properties. Consequently, we achieved CsPbBr3 films characterized by enlarged crystal size, complete coverage, high purity, and without pinhole presence, leading to a best-performed efficiency of 10.35% and a higher Voc of up to 1.580 V compared to the power conversion efficiency (PCE) of 8.35% and a Voc of 1.442 V of the control device, along with exceptional operational stability.