Enhanced Carrier Diffusion Enables Efficient Back‐Contact Perovskite Photovoltaics

Abstract

Back‐contact architectures offer a promising route to improve the record efficiencies of perovskite solar cells (PSCs) by eliminating parasitic light absorption. However, the performance of back‐contact PSCs is limited by inadequate carrier diffusion in perovskite. Here, we report that perovskite films with a preferred out‐of‐plane orientation show improved carrier dynamic properties. With the addition of guanidine thiocyanate, the films exhibit carrier lifetimes and mobilities increased by 3–5 times, leading to diffusion lengths exceeding 7 μm. The enhanced carrier diffusion results from substantial suppression of nonradiative recombination and improves charge collection. Devices using such films achieve reproducible efficiencies reaching 11.2 %, among the best performances for back‐contact PSCs. Our findings demonstrate the impact of carrier dynamics on back‐contact PSCs and provide the basis for a new route to high‐performance back‐contact perovskite optoelectronic devices at low cost.

Unveiling Local Current Behavior and Manipulating Grain Homogenization of Perovskite Films for Efficient Solar Cells

“…While the SPO PCEs for both types of devices were similar, the integrated J sc of ordered-perovskite devices was slightly higher, reinforcing the positive impact of crystal orientation (Figure i,j). Currently, there is a widespread discussion on improving the performance of perovskite macroscopic devices through microcrystal orientation. − Our experiments have shown that there is a strong anticorrelation between current and external bias in random-perovskite films at the microscopic level. However, the ordered-perovskite films exhibit significant improvements in current homogeneity and optoelectronic properties.…”