The electron transport layer (ETL) in a perovskite solar cell extracts photo-generated electrons from the perovskite absorber and prevents their recombination with holes. Commonly used ETL’s are organic layers comprised of fullerenes or fullerene derivatives such as C60 and PCBM. Inorganic ETL’s are attractive due to their barrier functionality against moisture and heat. They can be used as buffer layers for sputtering transparent conductive oxides to fabricate tandem devices, and they are compatible with high-temperature encapsulation. Inorganic ETL’s also exhibit higher carrier mobility and mechanical stability when compared to their organic counterparts.
Atmospheric Pressure Chemical Vapor Deposition (AP-CVD) is an attractive and cost-effective method of depositing inorganic ETL’s. The open air process requires no high vacuum or expensive equipment and can be done at low temperatures. As a result, the energy costs are low and the process is scalable to large area device fabrication.
Current methods of perovskite solar cell fabrication involve using spin-coating techniques in inert atmospheres which are entirely not scalable for large area perovskite solar cell production. In RSPP perovskites, an ultrasonic spray delivers a wet film which is then immediately converted to a perovskite film by an open-air atmospheric plasma through a combination of reactive oxygen and nitrogen species (RONS), UV photons, and hot convective gases. The entire process occurs in under one second and does not require lengthy anneal times. We are able to fabricate long strips of high-quality perovskite films, which are separated into sub-cells and integrated into a full solar module.
J.P. Chen*, F. Hilt*, N. Rolston, R.H. Dauskardt, “Scalable open-air deposition of compact ETL TiOx on perovskite for fullerene-free solar cells”, Journal of Materials Chemistry A, 2020, DOI: 10.1039/D0TA08554E