Diamine surface passivation and postannealing enhance the performance of silicon-perovskite tandem solar cells

Journal article

We show that the use of 1,3-diaminopropane (DAP) as a chemical modifier at the perovskite/electron-transport layer (ETL) interface enhances the power conversion efficiency (PCE) of 1.7 eV band gap mixed-halide perovskite containing formamidinium and Cs single-junction cells, primarily by increasing the open-circuit voltage (VOC) from 1.06 to 1.15 V. We find that adding a postprocessing annealing step after C60 evaporation further improves device performance. Specifically, the fill factor (FF) increases by 20% in the DAP + postannealing devices compared to the control. Using hyperspectral photoluminescence microscopy, we demonstrate that annealing helps improve compositional homogeneity at the electron-transport layer (ETL) and hole-transport layer (HTL) interfaces of the solar cell, which prevents detrimental band gap pinning in the devices and improves C60 adhesion. Using time-of-flight secondary ion mass spectrometry, we show that DAP reacts with formamidinium (FA+) present at the surface of the perovskite structure to form a larger molecular cation, 1,4,5,6-tetrahydropyrimidinium (THP+), which remains at the interface. Combining the use of DAP and annealing the C60 interface, we fabricate Si-perovskite tandems with a PCE of 25.29%, compared to 23.26% for control devices. Our study underscores the critical role of the chemical reactivity of diamines at the surface and the thermal postprocessing of the C60/Lewis-base passivator interface in minimizing device losses and enhancing solar-cell performance of wide-band-gap mixed-cation mixed-halide perovskites for tandem applications.

Authors: Taddei, M; Contreras, H; Doan, H-N; McCarthy, DP; Seo, S

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Chemical Society
• Journal: ACS Applied Materials and Interfaces
• Volume: 17
• Issue: 26
• Pages: 38754–38762
• Place of publication: United States
• Publication date: 2025-06-17
• Acceptance date: 2025-06-10
• DOI: 10.1021/acsami.5c07722
• EISSN: 1944-8252
• ISSN: 1944-8244
• Pmid: 40527288
• Language: English
• Keywords: passivation; diamine; perovskite; solar cell; Si-perovskite tandem