Out-of-Glovebox Integration of Recyclable Europium-Doped CsPbI3 in Triple-Mesoscopic Carbon-Based Solar Cells Exceeding 9% Efficiency

CsPbI3, perovskites are attracting huge interest for their inorganic structure and thanks to a bandgap of 1.69-1.78 eV that makes them suitable for application in tandem solar cells with silicon. Herein, all-inorganic hole-transporting-layer (HTL)-free carbon-based CsPbI3 perovskite solar cells (mC-PSCs) are fabricated, for the first time, by infiltrating CsPbI3 solutions enriched with precursors of Europium into triple mesoscopic structures with mesoporous (mp) materials (mp-TiO2/mp-ZrO2/mp-Carbon). The use of Europium is beneficial to mitigate lattice defect formation during the reaction. Drop casting of the solution is done in air and the black y-phase formation is promoted under dynamic nitrogen flow during high-temperature annealing (350 degrees C), which is preferred to low-temperature treatments to maximize perovskite phase stability. The preparation protocol entrusts the devices with the best power conversion efficiencies (PCEs) of 9.2% and 5.2% using EuI2 and EuCI3, respectively. Recorded PCE is considerably lower (<2%) in the reference devices prepared without Europium. In addition, the Eu-based devices are recycled to reconvert the photo-inactive yellow s-phase into the photo-active black gamma-phase with the devices losing only approximate to 10% of the efficiency of the original device. Thus, it is demonstrated that mC-PSCs recycling is feasible by exploiting the special feature of the high-temperature black gamma-phase-reversibility.

Automated summary

In this study, all-inorganic perovskite solar cells were fabricated, and the power conversion efficiency was significantly improved. The addition of europium precursors helped reduce lattice defects. High-temperature annealing was used to enhance the stability of the perovskite phase. Furthermore, the recycling of the cells allowed for the recovery of their performance.