Stepping toward Portable Optoelectronics with SnO 2 Quantum Dot-Based Electron Transport Layers.

With a power conversion efficiency (PCE) of more than 25%, perovskite solar cells (PSCs) have shown an immense potential application for solar energy conversion. Owing to lower manufacturing costs and facile processibility via printing techniques, PSCs can easily be scaled up to an industrial scale. The device performance of printed PSCs has been improving steadily with the development and optimization of the printing process for the device functional layers. Various kinds of SnO 2 nanoparticle (NP) dispersion solutions including commercial ones are used to print the electron transport layer (ETL) of printed PSCs, and high processing temperatures are often required to obtain ETLs with optimum quality. This, however, limits the application of SnO 2 ETLs in printed and flexible PSCs. In this work, the use of an alternative SnO 2 dispersion solution based on SnO 2 quantum dots (QDs) to fabricate ETLs of printed PSCs on flexible substrates is reported. A comparative analysis of the performance and properties of the obtained devices with the devices fabricated employing ETLs made with a commercial SnO 2 NP dispersion solution is carried out. The ETLs made with SnO 2 QDs are shown to improve the performance of devices by ∼11% on average compared to the ETLs made with SnO 2 NPs. It is found that employing SnO 2 QDs can reduce trap states in the perovskite layer and improve charge extraction in devices.