Abstract
Wide-bandgap (WBG) mixed-halide perovskites with high Br content, which are employed as the front cell material in perovskite–organic tandem solar cells (TSCs), often suffer from initial halide-mixing inhomogeneity and light-induced halide segregation1–3, limiting the performance of perovskite–organic TSCs. Here, we introduced a photo-transformable additive 4-[3-(trifluoromethyl)-3H-diazirin-3-yl]benzylamine (TDB) into the WBG perovskite precursor solution to establish a two-stage strategy for stabilizing the mixed-halide phase. During crystallization, TDB improves the initial halide homogeneity by suppressing the rapid precipitation of the Br-rich phase and accelerating halide mixing upon annealing. During operational illumination, TDB undergoes transformation to form a new species with stronger adsorption on the perovskite grain-boundary surfaces, which inhibits the formation of iodide-related defects, suppresses defect-assisted carrier trapping and ion migration, thereby mitigating light-induced halide segregation4–6. The representative WBG perovskite (Eg = 1.88 eV) solar cell achieved a power conversion efficiency (PCE) of 20.01%, with an open-circuit voltage of 1.42 V, a fill factor of 85.13% and improved stability under illumination. By integrating the WBG perovskite solar cell into a monolithic perovskite–organic TSC, we achieved a PCE of 28.80% with a certified steady-state PCE of 28.04%. The perovskite–organic TSC retained 90% of its initial PCE after 625 h of operation under the ISOS-L-1 protocol.
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Wu, R., Qin, S., Zou, T. et al. Perovskite–organic tandem solar cells with a photo-transformable stabilizer. Nature (2026). https://doi.org/10.1038/s41586-026-10869-x
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DOI: https://doi.org/10.1038/s41586-026-10869-x
Facts Only
* Wide-bandgap (WBG) mixed-halide perovskites with high Br content are used as front cell material in perovskite–organic tandem solar cells (TSCs).
* A photo-transformable additive, 4-[3-(trifluoromethyl)-3H-diazirin-3-yl]benzylamine (TDB), was introduced into the WBG perovskite precursor solution.
* TDB improved initial halide homogeneity by suppressing rapid precipitation of the Br-rich phase during crystallization and accelerating halide mixing upon annealing.
* During illumination, TDB transforms to a species that forms stronger adsorption on perovskite grain-boundary surfaces.
* This transformation inhibits the formation of iodide-related defects.
* The additive suppresses defect-assisted carrier trapping and ion migration, mitigating light-induced halide segregation.
* A representative WBG perovskite cell achieved a PCE of 20.01% with an open-circuit voltage of 1.42 V and a fill factor of 85.13%.
* The integrated perovskite–organic TSC achieved a PCE of 28.80% with a certified steady-state PCE of 28.04%.
* The tandem cell retained 90% of its initial PCE after 625 h of operation under the ISOS-L-1 protocol.
Executive Summary
Full Take
The development introduces a dynamic stabilization mechanism where a chemical component actively participates in both the fabrication and operational stages to manage inherent material instabilities. The pattern observed is an attempt to use photo-transformability—a change induced by light—to enforce thermodynamic stability on the perovskite structure against segregation phenomena, which are generally driven by kinetic instabilities in mixed-halide systems. The focus shifts from static stabilization (using bulk additives) to dynamic, surface-mediated control during operation. This suggests a paradigm shift where functional additives are not just reactants but active modulators of long-term device reliability.
The implications suggest that performance limitations in high-efficiency tandem cells are not solely rooted in material stoichiometry but critically depend on defect dynamics influenced by external stimuli (light). The success lies in designing a component whose photo-induced state offers specific surface chemistry advantages, effectively creating kinetic barriers against ion migration and defect accumulation at grain boundaries. Future investigation should focus on characterizing the exact energetic barrier associated with the TDB transformation products and precisely quantifying how this interfacial adsorption correlates with long-term operational stability beyond the 625-hour benchmark. Furthermore, understanding the role of halide segregation in tandem architectures—where different materials interact across interfaces—provides a deeper context for why controlling halide distribution is paramount to achieving monolithic efficiency gains.