Dual interfacial engineering to improve ultraviolet and near-infrared light harvesting for efficient and stable perovskite solar cells

Abstract

The light loss caused by the incomplete utilization of the solar energy spectrum is a key factor that impedes the photoelectric conversion efficiency of perovskite solar cells (PSCs). Hence, reducing the light escape through enhancing the utilization of ultraviolet (UV) light, and expanding the response of PSCs in the near-infrared (NIR) range is the key factor to further improve the photoelectric conversion efficiency (PCE) of PSCs. However, there is a lack of literature on engineering UV and NIR light harvesting at the same time. Herein, the NaYF4:Ce,Tb@NaYF4 core–shell nanocrystals with efficient photon downconversion ability from UV to visible are designed to be embedded in the electron transporting layer (ETL), which serves as the photon downconverters and defect passivators, successfully improving the light response in both UV and visible region. The CIGSe quantum dots (QDs) with excellent infrared light harvesting ability, together with the plasmonic Au nanorods (NRs), are assembled in the hole transporting layer (HTL) to expand and improve the NIR light harvesting. The light response of the PSCs was successfully broadened to the NIR region from 800 to 920 nm. As a result, the champion PSC device insulating with NaYF4:Ce,Tb@NaYF4 nanocrystals and CIGSe QDs demonstrates a remarkably increased PCE from 19.38% to 22.60%. The modified PSC devices also demonstrate highly improved UV and long-term stability. This work suggests a universal strategy to improve the UV and near-infrared light harvesting of PSCs, which is of great importance for fabricating PSCs with response to full spectrum.