Amorphous antimony sulfide nanoparticles construct multi-contact electron transport layers for efficient carbon-based all-inorganic CsPbI2Br perovskite solar cells

The traditional TiO2 electron transport layer (ETL) is modified with amorphous antimony sulfide nanoparticles with mercaptopropionic acid ligands to form a multi-contact ETL. The multi-contact ETL exhibits better conductivity, higher electron transport effect and weaker charge recombination. Additionally, it can assiste to form high quality of CsPbI2Br films. Moreover, compared to the device with conventional TiO2 ETL, the one with the multi-contact ETL has good humidity and thermal stability. [Display omitted] •The amorphous Sb2S3 NPs with MPA ligands are prepared.•A multi-contact ETL is prepared with Sb2S3-MPA NPs dispersing on TiO2 ETL.•The multi-contact ETL shows high charge transport and low recombination.•The multi-contact ETL also can well assist to form high quality CsPbI2Br film.•The champion PCE of the carbon-based CsPbI2Br PSC achieves as high as 14.59 %. Titanium dioxide (TiO2) layers usually have been applied in perovskite solar cells (PSCs) as traditional electron transport layers (ETLs). However, it has some flaws such as charge recombination and low electron transport rate. Herein, we synthesize amorphous antimony sulfide nanoparticles (Sb2S3 NPs) with uniform distribution of elements and the particle size is about 20 nm by hot injection method, and the nanoparticles are ligand-exchanged with mercaptopropionic acid (MPA). After detailed concentration adjustment, the surface of TiO2 ETL is modified and a multi-contact ETL is prepared. Compared to the conventional TiO2 ETL, the multi-contact ETL exhibits better conductivity, which gives suppressed charge recombination and more effective charge transport at the ETL/perovskite interface. Moreover, the multi-contact ETL can assist to form high quality of CsPbI2Br films. At the same time, the best efficiency of the prepared carbon-based CsPbI2Br PSC achieves as high as 14.59 %, and it still can maintain the initial efficiency of about 96.4 % after continuously heating at 85 °C for 28 days under nitrogen condition.