Triple-halide wide-bandgap perovskites tailored via facile organic halide treatment for high-performance perovskite/Cu(In,Ga)Se2 tandem solar cells

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2023-11, Vol.476, p.146825, Article 146825
• Main Authors: Tran, Huyen, Naqvi, Syed Dildar Haider, Kim, Kihwan, Lee, Ahreum, Oh, Seungju, Siddique, Yasir, Ullah, Asmat, Ali, Shah Syed Fawad, Park, Minwoo, Hong, Sungjun, Ahn, Sejin, Gwak, Jihye, Jeong, Inyoung
• Format: Article
• Language: English
• Subjects: Copper indium gallium selenide; Defect passivation; Perovskite solar cell; Tandem cell
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2023.146825

•A facile organic halide post-treatment for triple-halide wide-bandgap perovskite was proposed.•Concurrent diffusion of organic halide salt results in reconstruction of perovskite film.•The reconstructed perovskite exhibits suppressed nonradiative recombination and reduced Urbach energy.•Four-terminal perovskite/Cu(In,Ga)Se2 tandem cells achieve a power conversion efficiency of 24.5%. Wide-bandgap (Eg) perovskites (PVSK) are important materials for realizing high-efficiency tandem devices that surpass the efficiency limit of single-junction solar cells. However, they suffer from phase separation and open-circuit voltage (Voc) loss. This study demonstrated a facile fabrication strategy of highly efficient and stable wide-Eg PVSKs through an organic halide surface treatment with formamidinium bromide to CH3NH3PbI3-xClx. The concurrent diffusion of organic cations and halide ions from the surface into bulk PVSK results in the complete conversion of the PVSK crystallinity to a cubic phase, eliminating segregated secondary phases and reducing unreacted PbI2. Br incorporation induces halide redistribution, resulting in the formation of triple-halide wide-Eg PVSK. The complete reconstruction of the bulk and surface of PVSK by surface post-treatment suppresses trap-induced nonradiative recombination and decreases the Urbach tail energy. Inverted PVSK solar cells based on the reconstructed PVSK exhibit enhanced photovoltaic performance with a low Voc deficit and high stability. In addition, we demonstrated a four-terminal (4-T) tandem device based on the triple-halide wide-Eg PVSK as a top cell combining with a Cu(In,Ga)Se2 bottom cell, achieving a power conversion efficiency of 24.5 %.