Effect of TiO2 particle size and layer thickness on mesoscopic perovskite solar cells.

Highlights • Electron injection and transport properties of mesoporous layer containing TiO 2 nanoparticles are investigated. • The photovoltaic properties are poor with small TiO 2 particles and thick mesoporous layers. • This poor performance is due to the increase of the area of the TiO 2 /TiO 2 interface. • The TiO 2 /TiO 2 interfacial resistance largely influences the photovoltaic parameters. Abstract Mesoporous TiO 2 (mp-TiO 2) layers are commonly used as electron transport layers in perovskite solar cells, which help to extract electrons from the perovskite light-absorbing layer and transport them to the electrodes. We investigated the effects of the layer thickness of mp-TiO 2 and particle size of TiO 2 on photovoltaic properties, in terms of the surface area of the mp-layer and the interfacial areas of the TiO 2 nanoparticles in the mp-layer. Various mp-TiO 2 layers with thicknesses of 150, 250, and 400 nm and particle sizes of 25 nm and 41 nm were prepared to compare the photovoltaic properties of such layer-containing perovskite solar cells. Time-resolved photoluminescence decay and impedance studies showed that interfacial resistance as well as perovskite-to-TiO 2 charge injection are important factors affecting photovoltaic performance. The deterioration of the photovoltaic parameters with increasing TiO 2 /TiO 2 interfacial area also confirms that the interfacial series resistance that arises from these connections should be reduced to enhance the performance of mesoscopic perovskite solar cells. [ABSTRACT FROM AUTHOR]