New insights in construction of three-dimensional donor/acceptor interface for high performance perovskite solar cells: The preparation of wolf tooth stick-like TiO2

Abstract

Organic-inorganic hybrid perovskite solar cells (PSCs) have recently been considered as emerging candidates for the new generation of photovoltaic devices due to their outstanding properties. However, the challenge in carrier transport such as the unfavorable nonradiative recombination in the active layer and the finite stability at device interfaces limit their further commercialization. One of the major obstacles is that the metastable state at donor/acceptor (D/A) interfaces limits the device stability. Thus, how to improve the stability of the interface is one of the main concern. Herein, a new strategy is proposed to building stable D/A interface by introducing the three-dimensional (3-D) structure in PSCs, where a novel wolf tooth stick-like TiO2 (wts-TiO2) is prepared as electron transport material (ETM). The as-prepared devices exhibit excellent performance with accelerated charge transport, reduced nonradiative recombination, expanded D/A interface, and shortened internal photoexcitons diffusion distance. As a result, a top PCE of 19.6% was obtained. Moreover, the wts-TiO2 based solar cells showed excellent long-term stability, which maintained over 81.5% of the initial efficiency after 30 days. Our work provided new insights in fabrication of high-performance perovskite solar cells.