Efficient and stable CsPbI3 perovskite quantum dots enabled by in situ ytterbium doping for photovoltaic applications

Colloidal perovskite nanocrystals, or quantum dots (QDs), have quickly emerged and exhibited unique opportunities for optoelectronic applications. This is due to their excellent optical and photovoltaic properties as well as composition tunability. Currently, there are only a limited number of publications correlating QD synthesis optimization with relevant device performance. Here, CsPbI3 QDs have been successfully synthesized and displayed improved optoelectrical properties by implementing an in situ ytterbium (Yb) doping strategy during synthesis. Systematic investigations were carried out to examine the effects of Yb-doping. Preliminary experimental results indicated that Yb3+ lanthanide cations could effectively reduce the number of defects and trap states caused by surface and lattice vacancies. This result contributes to an improvement in QD photoluminescence quantum yield (PLQY), material crystallinity, thermal stability and carrier transport. Consequently, the solar cells adopting optimally Ybdoped CsPbI3 QDs achieved the best power conversion efficiency (PCE) of 13.12% and displayed significantly improved storage stability under ambient conditions. These results indicate that in situ doping has great potential to improve the quality of the resultant perovskite QDs. This approach can provide a new path to a breakthrough in QD based solar cell technology.