Vacuum-Deposited Perovskite Solar Cells Enhanced by Controlled Crystallization

Perovskite solar cells (PSCs) have long been heralded as a game-changing technology in the quest for efficient, low-cost renewable energy. While solution processing has dominated the fabrication of PSCs, vacuum deposition techniques present a promising alternative with potential for scalability and environmental benefits. However, until recently, vacuum-deposited PSCs have lagged behind their solution-processed counterparts in terms of performance and stability.

A new study by Xu, Pan, Shi, and colleagues published in Nature Energy (2026) introduces a novel approach that significantly propels vacuum-deposited PSCs to the forefront of solar cell technology. The team focused on the critical phase of solid-state crystallization, employing formamidinium acetate to finely control the crystal growth pathway, thereby overcoming long-standing challenges inherent to vacuum deposition.

The researchers demonstrated that formamidinium acetate reacts directly with lead iodide (PbI₂) to create FAPbI₃ seed layers. This insight is pivotal because it lowers the energy barrier required for the solid-state conversion of precursor materials into the perovskite structure, beginning with the δ-phase and subsequently transforming into the highly desirable α-phase renowned for its photovoltaic properties. By facilitating this smoother phase transition, the manufacturing process becomes more efficient and yields higher-quality perovskite films.

An additional and equally crucial benefit of the acetate lies in its role as a passivating agent at grain boundaries within the perovskite layer. These boundaries often act as defect sites that encourage non-radiative recombination, a process that typically diminishes solar cell performance by wasting absorbed energy as heat rather than electricity. The excess acetate effectively suppresses these defects, which in turn enhances the radiative efficiency of the device.

As a result of these advancements, the fully vacuum-deposited PSCs achieved an impressive power conversion efficiency (PCE) of 25.53%, a benchmark that rivals many top-tier solution-processed solar cells. Complementing this, the devices exhibited an electroluminescence external quantum efficiency of 18.38%, underscoring the high quality and low defect density of the perovskite films produced by this method.

The solvent-free nature of vacuum deposition also contributes positively to device longevity. The newly developed PSCs maintained over 95% of their initial efficiency after more than 1,000 hours of continuous operation under the ISOS-L-1 stability testing protocol. This durability addresses a significant hurdle in PSC commercialization, as long-term operational stability has remained a persistent concern.

This advancement not only validates the feasibility of fully vacuum-deposited PSCs for high-efficiency applications but also opens pathways for more environmentally friendly and scalable manufacturing processes. By harnessing controlled solid-state crystallization with formamidinium acetate, the study bridges the performance gap between vacuum and solution processing methods.

With this breakthrough, vacuum-deposited perovskite solar cells stand at the cusp of becoming viable candidates for commercial photovoltaic technologies. These findings could accelerate the deployment of next-generation solar modules that combine high efficiency, stability, and sustainability—key criteria for the global energy landscape’s future.

As the field continues to explore new materials and processing techniques, innovations like those reported here highlight the instrumental role of chemistry and materials science in shaping the energy technologies of tomorrow.