Improved photovoltaic performance of perovskite solar cells based on three-dimensional rutile TiO₂ nanodendrite array...

In order to explore high performance and stable perovskite solar cells (PSCs), the design and optimization of electron transport layer (ETL) have been paid more and more attention. Vertically oriented, one-dimensional (1D) TiO2 nanostructured array films are considered superior ETLs because of their rapid electron transporting property and open pore architectures. In this study, a three-dimensional (3D) rutile TiO2 nanodendrite array (RTNDA) film containing 1D trunks and branches was fabricated through second hydrothermal treatment of 1D rutile TiO2 nanorod array (RTNRA) film hydrothermally grown on a fluorine tin oxide (FTO) conductive glass. The resulting 3D-RTNDA film not only facilitates close contact with mixed-ion perovskite (Cs0.05(FA0.83MA0.17)0.95Pb(I0.9Br0.1)3) film, but also promotes the formation of a perovskite layer with larger crystal grain sizes. Both can efficiently retard the interface charge recombination, and thus result in a significantly improved power conversion efficiency (PCE) of 18.0%, improved by 20% as compared to that (15.0%) of the device fabricated with the 1D-RTNRA film. Spectroscopic, electrochemical and photoelectrochemical measurements indicate that the improved photovolatic performance can be mainly ascribed to the largely suppressed hysteresis effect, the increased open-circuit voltage and fill factor stemming from the more effective hole blocking and electron transport. The results presented here demonstrate that 3D-RTNDA film with 3D rutile TiO2 hierarchical nanoarchitecture is a promising ETL selection in designing high-performance PSCs.