Control of TiO2 electron transport layer properties to enhance perovskite photovoltaics performance and stability.

This study demonstrates the effect of electron collection and transportation for TiO 2 electron transport layer (ETL) of the mesoscopic perovskite solar cells (PSCs). The influence of compact TiO 2 layer (c-TiO 2) with various spray cycles, the particle size effect of mesoporous TiO 2 (meso-TiO 2) film and post-treatment of TiO 2 electrode for perovskite solar cells have been studied systematically. We further optimize the meso-TiO 2 thickness to enhance the electron collection and transport efficiency and to reduce the anomalous J-V hysteresis phenomenon of PSCs. After adjusting the fabrication process of TiO 2 ETL, the highest performance of small cell PSC shows the power conversion efficiency (PCE) of 19.39% in the reverse scan and 19.12% in the forward scan, respectively. A sub-module PSC within an active area of 11.7 cm2 exhibits impressive PCE of 16.03% under the illumination of 100 mW/cm2 (AM1.5G). Moreover, it also shows an outstanding PCE of 25.49% under the illumination of 6000 lx of T5 indoor light source. Image 1 • The various sizes of high purity anatase phase TiO 2 nanoparticles (NPs) are synthesized for perovskite solar cells. • The 2L c-TiO 2 and 150 nm meso-TiO 2 film with 22 nm NPs showed the best properties. • Effective charge separation at the perovskite/electron transport layer interface, resulting in the higher FF and V OC. • Smaller TiO 2 particle size has better electron extraction efficiency and results in a less J-V hysteresis behavior. [ABSTRACT FROM AUTHOR]