Reinforcing built-in electric field to enable efficient carrier extraction for high-performance perovskite solar cells

Perovskite solar cells (PSCs) have gained significant attention in recent years due to their low fabrication cost, solution-based processing, potential for flexibility and large-scale solar energy conversion. The performance of PSCs depends on effectively separating and collecting the photogenerated charge carriers before they recombine and lose excess energy. Therefore, efficient carrier extraction is crucial for achieving high-performance PSCs. The built-in electric field (BEF) within PSCs serves as the driving force for extracting carriers to their corresponding electrodes. Reinforcing the BEF can reduce carrier recombination in the bulk phase/interface, facilitate carrier separation and extraction, and minimize energy losses in PSCs. Up to now, numerous efforts have been made to enhance the BEF and further improve the photovoltaic performance of PSCs. This review first describes the carrier separation and extraction mechanism influenced by the BEF. It then summarizes various strategies used to enhance the BEF in PSCs, including forming semiconductor junctions, regulating energy levels through dipole layers and functional layer modifications, constructing a ferroelectricity polarization electric field (PEF) within PSCs, and mitigating the surface charge accumulation caused by ion migration. Finally, this review discusses the prospects for designing an enhanced BEF to promote the continuous development of high-performance PSCs. This review provides useful insights for further analyzing the mechanism of the BEF in PSCs and achieving breakthroughs in the efficiency of PSC devices through field effect passivation.