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Abstract:

July 4, 2025

Abstract:

Tandem photovoltaics hold great potential to surpass the efficiency limit of single-junction solar cells. Detrimental structural defects and chemical reactions at buried interfaces of subcells considerably impede the performance of integrated tandems. Here, we devise a mercapto-functionalized mesoporous silica layer as a superstructure at the buried interface to modulate the crystallisation, eliminate nanovoids, passivate defects, and suppress the oxidation of Sn(II) in the tin–lead perovskite films, contributing substantially to reduce charge carrier losses and improve stability in positive-intrinsic-negative structured devices. Consequently, the tin–lead perovskite single-junction cells show efficiency values of up to 23.7% with the best open-circuit voltage of 0.89 V. With the enhanced subcells, our double-junction tandems show efficiency values of 29.6% (certified 29.5% and steady-state 28.7%) and 24.7% on solar cells and 11.3 cm2 mini-modules, respectively. Encapsulated tandems maintain 90% of initial efficiency after 445 h of maximum power point tracking under simulated 1-sun illumination.

Abstract:

Metal-halide perovskite solar cells have achieved power conversion efficiencies comparable to those of silicon photovoltaic (PV) devices, approaching 27% for single-junction devices. The durability of the devices, however, lags far behind their performance. Their practical implementation implies the subjection of the material and devices to temperature cycles of varying intensity, driven by diurnal cycles or geographical characteristics. Thus, it is vital to develop devices that are resilient to temperature cycling. This Perspective analyses the behaviour of perovskite devices under temperature cycling. We discuss the crystallographic structural evolution of the perovskite layer, reactions and/or interactions among stacked layers, PV properties and photocatalysed thermal reactions. We highlight effective strategies for improving stability under temperature cycling, such as enhancing material crystallinity or relieving interlayer thermal stress using buffer layers. Additionally, we outline existing standards and protocols for temperature cycling testing and we propose a unified approach that could facilitate valuable cross-study comparisons among scientific and industrial research laboratories. Finally, we share our outlook on strategies to develop perovskite PV devices with exceptional real-world operating stability.

Abstract:

Metal-halide perovskites are emerging as promising semiconductors for next-generation (opto)electronics. Due to their excellent optoelectronic and physical properties, as well as their processing capabilities, the past decades have seen significant progress and success in various device applications, such as solar cells, photodetectors, light-emitting diodes, and transistors. Despite their performance now rivaling or surpassing that of silicon counterparts, halide-perovskite semiconductors still face challenges for commercialization, particularly in terms of toxicity, stability, reliability, reproducibility, and lifetime. In this Roadmap, we present comprehensive discussions and perspectives from leading experts in the perovskite research community, covering various perovskite (opto)electronics, fundamental material properties and fabrication methods, photophysical characterizations, computing science, device physics, and the current challenges in each field. We hope this article provides a valuable resource for researchers and fosters the development of halide perovskites from basic to applied science.

Abstract:

All-perovskite tandem photovoltaics are a potentially cost-effective technology to power chemical fuel production, such as green hydrogen. However, their application is limited by deficits in open-circuit voltage and, more challengingly, poor operational stability of the photovoltaic cell. Here we report a laboratory-scale solar-assisted water-splitting system using an electrochemical flow cell and an all-perovskite tandem solar cell. We begin by treating the perovskite surface with a propane-1,3-diammonium iodide solution that reduces interface non-radiative recombination losses and achieves an open-circuit voltage above 90% of the detailed-balance limit for single-junction solar cells between the bandgap of 1.6-1.8 eV. Specifically, a high open-circuit voltage of 1.35 V and maximum power conversion efficiency of 19.9% are achieved at a 1.77 eV bandgap. This enables monolithic all-perovskite tandem solar cells with a 26.0% power conversion efficiency at 1 cm2 area and a pioneering photovoltaic-electrochemical system with a maximum solar-to-hydrogen efficiency of 17.8%. The system retains over 60% of its peak performance after operating for more than 180 h. We find that the performance loss is mainly due to the degradation of the photovoltaic component. We observe severe charge collection losses in the narrow-bandgap sub-cell that can be attributed to the interface degradation between the narrow-bandgap perovskite and the hole-transporting layer. Our study suggests that developing chemically stable absorbers and contact layers is critical for the applications of all-perovskite tandem photovoltaics.