Thiosulfate-terminated CdSe quantum dots for improving the performance and stability of perovskite solar cells

Cadmium selenide (CdSe) quantum dots (QDs) as functional interface layer have been used to improve the performances of perovskite solar cells (PSCs). However, the optimization of PSCs by CdSe QDs has some challenges of inferior performances for charge transportation, and interface defects, which are not conducive to the development of power conversion efficiency (PCE). Here, sodium thiosulfate capped CdSe QDs (S2O32--CdSe QDs) are prepared as interface modifiers to improve the performances of PSCs. The S2O32--CdSe QDs can effectively passivate defects and reduce interfacial nonradiative recombination, Moreover, the S2O32--CdSe QDs regulate the energy level of perovskite film. In addition, the S2O32--CdSe QDs form an interface layer to increase moisture resistance and improve the stability of PSCs. As a result, the devices with S2O32--CdSe QDs show an improved power conversion efficiency (PCE) of 22.57 %. Meanwhile, the stabilities of the unencapsulated device with S2O32--CdSe QDs under 25 degrees C with a humidity of 30 %-40 %, and 85 degrees C in N2 heat both perform better than the control devices.