Researchers from EPFL, CSEM and Empa have demonstrated a cell design combining additive and substrate engineering that yields consistently high power conversion efficiencies and discussed various design aspects that are important for reproducibility and performance.
The team presented two key developments with a synergetic effect that boost the PCEs of tandem devices with front-side flat Si wafers—the use of 2,3,4,5,6-pentafluorobenzylphosphonic acid (pFBPA) in the perovskite precursor ink that suppresses recombination near the perovskite/C60 interface and the use of SiO2 nanoparticles under the perovskite film that suppress the enhanced number of pinholes and shunts introduced by pFBPA, while also allowing reliable use of Me-4PACz as a hole transport layer.
Integrating these developments in an optically and electrically optimized tandem device (e.g., with a durable Si cell) yielded reproducible PCEs of 30 ± 1%, and a certified maximum of 30.9%.
