Stepping toward Portable Optoelectronics with SnO₂ 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 SnO₂ 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 SnO₂ ETLs in printed and flexible PSCs. In this work, the use of an alternative SnO₂ dispersion solution based on SnO₂ 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 SnO₂ NP dispersion solution is carried out. The ETLs made with SnO₂ QDs are shown to improve the performance of devices by ∼11% on average compared to the ETLs made with SnO₂ NPs. It is found that employing SnO₂ QDs can reduce trap states in the perovskite layer and improve charge extraction in devices.