Suppressing\nCharge Extraction Loss in Quantum Dot\nInfrared Photovoltaics by Optimizing the Charge Transport Layer

Infrared\nsolar cells (IRSCs), capable of converting low-energy\ninfrared photons to electron–hole pairs, are promising infrared\noptoelectronic devices because of their extended utilization region\nof the solar to short-wavelength infrared region. For PbS QDs IRSCs,\ncharge extraction loss, easily generated at the interfaces, has been\none of the dominate obstacles impeding the improvement of device efficiencies\ndue to too many trap states and mismatched energy levels between the\nphotoactive layer and electron transport layer (ETL). Herein, an advanced\nZnO ETL was developed to improve the extraction of photogenerated\ncharges from the PbS QD photoactive layer to ETLs. The advanced ETL\nfilm exhibited effectively suppressed trap states and better-matched\nenergy levels compared with the QD layer. As a consequence, high-performance\nPbS QD IRSCs with the highest infrared power conversion efficiencies\nof 1.26% under 1100 nm filtered solar illumination are achieved, suggesting\nan effective and facile route for enhancing the charge extraction\nin infrared photovoltaics.