Researchers from EPFL and CSEM recently fabricated efficient (>20 %) and stable (T80 ∼ 720 h) planar FAPbI3-based perovskite (1.54 eV) solar cells via a hybrid evaporation-spin coating process.
FAPbI3-based perovskite films were fabricated via a hybrid two-step evaporation-spin coating method in an inverted (p-i-n) configuration, and the effects of optimized parameters on the film growth and devices’ performances were investigated. Transferring these films into tandem devices atop single-side textured silicon heterojunction bottom cells, the team obtained an efficiency of >24 % under AM1.5 G illumination for monofacial devices with an active area of 1.21 cm2. Furthermore, the bifacial devices generated >27 mW cm−2 power output with 15 % rear illumination fraction.
The FAPbI3-based perovskites demonstrated high reproducible efficiencies and long-term stability in SJ devices and bifacial tandems. The scientists noted that these perovskite films turned out to be very sensitive to processing parameters, which further urges the need to optimize the fabrication protocols. In this work, the hybrid evaporation-spin coating of the FAPbI3-based perovskite was optimized, and for the first time, it is further integrated into the single side textured bifacial tandem of PSC/SHJ devices.
These process modifications yield high crystalline perovskite absorbers possessing large domains, which translated into a uniformity of the optoelectronic properties. Taking all these modifications into account, the team fabricated efficient bifacial PSC/SHJ devices with an average power output of 27 mW cm−2 with 15% illumination from back side.
