Compositionally Graded Absorber for Efficient and Stable Near‐Infrared‐Transparent Perovskite Solar Cells

Abstract

Compositional grading has been widely exploited in highly efficient Cu(In,Ga)Se2, CdTe, GaAs, quantum dot solar cells, and this strategy has the potential to improve the performance of emerging perovskite solar cells. However, realizing and maintaining compositionally graded perovskite absorber from solution processing is challenging. Moreover, the operational stability of graded perovskite solar cells under long‐term heat/light soaking has not been demonstrated. In this study, a facile partial ion‐exchange approach is reported to achieve compositionally graded perovskite absorber layers. Incorporating compositional grading improves charge collection and suppresses interface recombination, enabling to fabricate near‐infrared‐transparent perovskite solar cells with power conversion efficiency of 16.8% in substrate configuration, and demonstrate 22.7% tandem efficiency with 3.3% absolute gain when mechanically stacked on a Cu(In,Ga)Se2 bottom cell. Non‐encapsulated graded perovskite device retains over 93% of its initial efficiency after 1000 h operation at maximum power point at 60 °C under equivalent 1 sun illumination. The results open an avenue in exploring partial ion‐exchange to design graded perovskite solar cells with improved efficiency and stability.

In situ investigations of interfacial degradation and ion migration at CH3NH3PbI3 perovskite/Ag interface

“…Perovskite solar cells are considered as one of the most promising candidates for the next generation photovoltaic technology due to the high power conversion efficiency (over 22.7%) and low cost fabrication [1,2]. However, despite these advantages, the long-term stability issues inhibit the further commercial development [3,4].…”

Structural and electronic properties of CdTe1-xSex films and their application in solar cells

“…Compositional gradings have been used in Cu(In,Ga)Se 2 solar cells for several years to achieve efficient carrier collection and reduced recombination [16]. More recently, this strategy has also been applied in perovskite solar cells [17]. …”

Realizing Stable Artificial Photon Energy Harvesting Based on Perovskite Solar Cells for Diverse Applications

“…Despite the high quality of the perovskite film, the device with high Br content and Cs doping shows an underwhelming PCE under both solar and LED light sources. The mismatched energy bands between the perovskite and the ETL should be blamed since the perovskite film with a large bandgap has a higher conduction band position 34–37…”