Enhanced Efficiency and Stability of Planar Perovskite Solar Cells Using a Dual Electron Transport Layer of Gold Nanoparticles Embedded in Anatase TiO2 Films.

Incorporating plasmonic nanostructures is a promising strategy to enhance both the optical and electrical characteristics of photovoltaic devices via more efficient harvesting of incident light. Herein, we report a facile fabrication scheme at low temperature for producing gold nanoparticles embedded in anatase TiO2 films, which can simultaneously improve the efficiency and stability of n-i-p planar heterojunction perovskite solar cells (PSCs). The PSCs based on rigid and flexible substrates with 0.2 wt % Au-TiO2/TiO2 dual electron transport layers (ETLs) achieved power conversion efficiencies up to 20.31 and 15.36%, superior to that of devices with TiO2 as a single ETL. Moreover, 0.2 wt % Au-TiO2/TiO2 devices demonstrated significant stability in light soaking, which is attributed to improved light absorption, low charge recombination loss, and enhanced carrier transport, and extraction with the plasmonic Au-TiO2/TiO2 dual ETL. The present work improves the practicability of high-performance and flexible PSCs by engineering the photogenerated carrier dynamics at the interface.

Enhancing Performance and Uniformity of Perovskite Solar Cells via a Solution-Processed C70 Interlayer for Interface Engineering.

Although some kinds of semiconductor metal oxides (SMOs) have been applied as electron selective layers (ESLs) for planar perovskite solar cells (PSCs), electron transfer is still limited by low electron mobility and defect film formation of SMO ESLs fabricated via low-temperature solution process. Herein, the C70 interlayer between TiO2 and (HC(NH2)2PbI3)x(CH3NH3PbCl3)1-x is prepared by spin-coating and low-temperature annealing for planar n-i-p PSCs. The resultant TiO2/C70 ESL shows good surface morphology, efficient electron extraction, and facilitation of high-quality perovskite film formation, which can be attributed to the suitable nanosize and the superior electronic property of C70 molecules. In comparison with pristine TiO2-based PSCs, the efficiency and hysteresis index are, respectively, enhanced 28% and reduced 76% by adding the C70 interlayer between TiO2 and perovskite on the basis of statistical data of more than 50 cells. With the main advantages of low-temperature process and optimized interface, the champion efficiency of PSCs on flexible substrates could exceed 12% in contrast with the above 18% on rigid substrate.