Hole-Transport Layer for High Current Density and Stability of Sn–Pb Perovskites and All-Perovskite Tandem Solar Cells
Sangheon Lee, Sang Jun Park, Min Soo Park, Lei Chen, Jae Ryoung Lee, Dong Hoe Kim, Kai Zhu
Abstract
Sn–Pb perovskites are essential for achieving efficient single-junction solar cells and all-perovskite tandem solar cells (APTSCs). Although Sn oxidation and defective surfaces were once major limitations, recent advances in intrinsic material quality have largely mitigated these issues. As a result, the HTL-related interface is now regarded as the primary bottleneck for device performance. To address the intrinsic drawbacks of PEDOT:PSS, chemical surface modification and additive strategies have been widely applied, and alternative HTLs, like polymeric, inorganic, or small-molecule HTLs, have also gained attention. These approaches offer improved energy-level alignment, high transparency, and enhanced chemical durability, leading to higher short-circuit current density and longer operational lifetime in both single-junction and tandem devices. In this Perspective, we highlight the key criteria and practical effects of HTL materials suitable for Sn–Pb perovskites.