Abstract
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.
Schematic of (a) champion device with structure of ITO/SnO2/PCBM/PbSe-PTLE/PbS-EDT/Au demonstrates that ultra-thin PCBM can alleviates charge recombination. (b) The PbSe quantum dot solar cell with device configuration of ITO/SnO2/PbSe-PTLE/PbS-EDT/Au and ITO/SnO2/PCBM/PbSe-PTLE/PbS-EDT/Au demonstrate 9.8% and 10.4% efficiency, respectively. [Display omitted]
•Solution phase transfer ligand exchange (PTLE) method was used to deposit PbSe quantum dot solid as an absorber.•The PbSe quantum dot solar cell demonstrated 9.8% efficiency by combining SnO2 as electron transport layer and PTLE deposited PbSe solid.•Ultra-thin PCBM layer was inserted between PbSe solid and SnO2 layer to modify the interface, which suppresses the carrier recombination at the interface.•The PbSe quantum dot device with a configuration of ITO/SnO2/PCBM/PbSe-PTLE/PbS-EDT/Au achieved 10.4% efficiency, the highest reported efficiency so far.