Engineering the electronic band structure of metal halide perovskites (MHPs) is at the heart of fundamental materials research and photovoltaic applications. However, reconfiguring the band structure in MHPs to optimize electronic properties remains challenging. Wang Zhiping et al. of Wuhan University reported a general strategy to construct near-edge states to improve carrier characteristics and thereby improve device performance. Near-edge states are designed around the valence band edge using theoretical predictions and built through custom materials engineering. These states were experimentally revealed by temperature-dependent time-resolved spectroscopy with an activation energy of approximately 23 millielectronvolts.
Such small activation energies enable extended carrier lifetimes with efficient carrier transition dynamics and low nonradiative recombination losses, as evidenced by millisecond lifetimes of microwave conductivity. The researchers fabricated an inverted structure battery, FTO/NiOx/Me-4PACz/FA0.9MA0.06Cs0.04PbI3/C60/BCP/Cu. F-PEAI molecules are used for bulk passivation, and PEAI molecules are used for surface passivation to build near-edge states in inverted batteries.
Achieved a championship efficiency of 25.4% (certified 25.0%) on a 0.07 cm2 cell, one of the highest efficiencies based on NiOx inversion . An efficiency of 23.6% (certified 22.7%) was achieved on a 1 cm2 cell. The most stable packaged cell retained 90% of its initial efficiency after 1,100 hours of maximum power point tracking under one sun illumination (100 mW/cm2) in 65 °C ambient air.
X. Zhu, W. Xiong, C. Hu, K. Mo, M. Yang, Y. Li, R. Li, C. Shen, Y. Liu, X. Liu, S. Wang, Q. Lin, S. Yuan, Z. Liu, Z. Wang, Constructing Ultra-Shallow Near-Edge States for Efficient and Stable Perovskite Solar Cells. Adv. Mater. 2024, 2309487.