Unravel the Charge‐Carrier Dynamics in Simple Dimethyl Oxalate‐Treated Perovskite Solar Cells with Efficiency Exceeding 22%

Abstract

Understanding the effect of additive on the interfacial charge‐carrier transfer dynamics is very crucial to obtaining highly efficient perovskite solar cells (PSCs). Herein, we designed a simple additive, dimethyl oxalate (DO), functioning as an effective defect passivator of perovskite grain boundaries via the coordination interaction between the carbonyl (C=O) and the exposed Pb2+. The modification with DO produces pinhole‐free and compact perovskite films, enhancing the transportation capability of carriers. As a consequence, the DO‐treated PSCs exhibited a power conversion efficiency (PCE) of 22.19%, which is significantly higher than that of the control device without additive (19.58%). More importantly, detailed transient absorption characterization reveals that the use of additive can decrease the hot‐carrier cooling dynamics, improve the carrier transfer, and eliminate nonradiative recombination in PSCs. This present work provides a profound understanding the additives effect on the carrier dynamics in PSCs toward the Shockley−Queisser limit.