Stable AgBiS2 near-infrared absorbers for thin film tandem photovoltaics

Shiling Dong; Yongjie Wang; Hae-Jun Seok; Mengyuan Huang; Edward Newton; Der Ying Chen; Yixin Wang; Xiaoyu Guo; Keisuke Takemoto; Dusan Ivanovic; Avari Roy; Yongge Yang; Grey Christoforo; Rebekah Fraser; Seongrok Seo; John O'Sullivan; Ha Kyung Park; Jack M. Woolley; Ji-Seon Kim; Ruy S. Bonilla; Henry J. Snaith; Qing Shen; Aditya Sadhanala; Lydia H. Wong; Robert L. Z. Hoye

arXiv · 2611.01797

Stable AgBiS2 near-infrared absorbers for thin film tandem photovoltaics

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Abstract

AgBiS2 has rapidly risen in efficiency as single-junction photovoltaics (PVs), but its potential for tandem PVs is unexplored. Herein, we perform optical modeling based on the experimental absorption spectrum of AgBiS2, revealing that, as the NIR sub-cell, efficiencies exceeding 47.9% are achievable in triple-junction tandems, superseding tandems using Pb/Sn perovskite NIR cells (35.9%). However, fulfilling this potential requires overcoming the limited transport properties of AgBiS2 nanocrystal films, which constrains film thicknesses to only 30-50 nm, severely restricting NIR response. A solution-phase ligand exchange process is herein developed, allowing one-step deposition of passivated AgBiS2 nanocrystals that maintain efficient charge-carrier extraction despite an order of magnitude increase in film thickness. These films enable 24.0%-efficient four-terminal tandems with visible-light-absorbing lead-halide perovskite sub-cells, and monolithic tandems successfully demonstrating voltage addition. AgBiS2 PVs have high stability, retaining >90% of the original efficiency after 3 months of storage in dry air without encapsulation. This work establishes the significant potential of AgBiS2 as a stable and scalable NIR absorber for tandem PVs.

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Shiling Dong, Yongjie Wang, Hae-Jun Seok, Mengyuan Huang, Edward Newton, Der Ying Chen, Yixin Wang, Xiaoyu Guo, Keisuke Takemoto, Dusan Ivanovic, Avari Roy, Yongge Yang, Grey Christoforo, Rebekah Fraser, Seongrok Seo, John O'Sullivan, Ha Kyung Park, Jack M. Woolley, Ji-Seon Kim, Ruy S. Bonilla, Henry J. Snaith, Qing Shen, Aditya Sadhanala, Lydia H. Wong, Robert L. Z. Hoye. 2026-11-01. Stable AgBiS2 near-infrared absorbers for thin film tandem photovoltaics. https://arxiv.org/abs/2611.01797

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