Shuaifeng Hu

Abstract:

While (111)-dominated perovskite films hold the potential for high-stability solar cells, most studies have primarily focused on modulating the (111) facets, overlooking the distribution and formation mechanism of the nondominant (100) facets. In this study, we delve into the (111) orientation via solvent regulation and investigate the evolution of facet distribution using various diffraction techniques. The findings reveal that simply stacking (111) facets does not inherently enhance solar cells. Instead, the distribution of nondominant (100) facets in (111)-dominated films significantly influences both photoelectric property and stability. These observations highlight the critical need to manage the interplay between dominant and nondominant facets. The study further offers strategies for addressing facet heterogeneity to achieve a uniform facet distribution. This research provides a comprehensive framework for understanding (111)-dominated perovskites and offers valuable guidance for designing high-performance perovskite solar cells.

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.

Abstract:

January 4, 2025