Synergistic effect of electron transport layer and colloidal quantum dot solid enable PbSe quantum dot solar cell achieving over 10 % efficiency
PbSe colloidal quantum dots (CQDs) possess the advantages of efficient multiple exciton generation (MEG) and a larger Bohr exciton radius compared with PbS CQDs, suggesting that PbSe CQDs can enable superior charge carrier generation and transport in optoelectronic devices. However, the efficiency of PbSe CQD solar cell is generally much lower than that of the PbS counterpart. This is due to the much more research effort dedicated to PbS CQDs solar cells, where effective strategies of ligand exchange, device configuration and charge transport layer engineering have been developed. Here, we combined ligand exchange and charge transport layer engineering to optimize PbSe CQD solar cell performance. The PbSe CQD absorber layer was deposited via one-step ink method on SnO2 with an ultra-thin PCBM serving as a modification interlayer. The champion device with the structure of ITO/SnO2/PCBM/PbSe-PbI2/PbS-EDT/Au achieved a 10.4% efficiency, which to the best of our knowledge the highest efficiency reported to date for PbSe CQD solar cell. This work demonstrates that PbSe CQDs are very promising for next-generation solution-processed photovoltaic technology with low cost and high performance.