Breakthrough in Vacuum-Processed Solar Cells Achieves Record Efficiency with Novel Deposition Method

Vacuum Processing Breakthrough for Solar Technology

Researchers have developed a fully thermally evaporated perovskite solar cell that achieves unprecedented efficiency while addressing key manufacturing challenges, according to a recent study published in Nature Photonics. The breakthrough reportedly represents a significant step toward commercial-scale production of perovskite photovoltaics using vacuum deposition methods traditionally reserved for conventional semiconductors.

Vacuum Processing Breakthrough for Solar Technology
Overcoming Manufacturing Limitations
Reverse Layer-by-Layer Innovation
Record Performance and Stability
Industrial Manufacturing Implications
Future Research Directions

Overcoming Manufacturing Limitations

Thermal evaporation has long been recognized as the most mature and stable method for preparing semiconductor films, analysts suggest, but its application to perovskite solar cells has faced persistent challenges. Sources indicate that previous attempts at fully thermally evaporated devices plateaued around 20% efficiency, substantially lagging behind the approximately 26% benchmark set by solution-processed counterparts.

The performance gap reportedly stemmed from multiple factors, including interfacial energy mismatches, inefficient carrier extraction, and fundamental differences in solid-phase crystallization dynamics compared to solution-based processes. Most fully thermally evaporated devices also relied on methylammonium lead iodide (MAPbI) with inherent instability issues, fundamentally limiting their potential, according to the research.

Reverse Layer-by-Layer Innovation

The research team introduced what they describe as a “reverse layer-by-layer evaporation strategy” that deposits formamidinium iodide (FAI) before inorganic precursors like cesium iodide and lead compounds. The report states that this sequence, combined with specific annealing conditions, promotes complete diffusion and reaction of layered solid-phase precursors.

Molecular dynamics simulations and in situ characterizations reportedly revealed that the evaporation sequence and annealing temperature played crucial roles in facilitating a phase transition from the lower-energy δ-phase to the desired α-phase. This process ultimately resulted in crystallization and growth occurring in a top-down direction, producing films with enhanced crystallinity and uniform component distribution.

Record Performance and Stability

The fully thermally evaporated perovskite solar cells with p-i-n structure demonstrated remarkable performance, according to the findings. Researchers reported achieving a power conversion efficiency of 25.19% for small-area cells (0.066 cm²) and 23.38% for scaled-up devices (1.00 cm²).

Perhaps equally significant, the devices exhibited exceptional operational stability, maintaining 95.2% of their initial efficiency after 1,000 hours of continuous operation at the maximum power point. This combination of high efficiency and robust stability addresses two critical requirements for commercial adoption, analysts suggest.

Industrial Manufacturing Implications

Thermal evaporation offers numerous advantages over solution processing, including precise process control, outstanding film uniformity, consistent substrate coverage, absence of harmful solvents, and exceptional reproducibility, according to industry observers. These characteristics make the technology particularly suitable for transitioning laboratory-scale perovskite solar cells to commercial modules.

The successful demonstration of a simplified evaporation strategy compatible with p-i-n structures represents significant progress, sources indicate, as most previous thermal evaporation studies had focused on n-i-p configurations with limited success in inverted devices.

Future Research Directions

While this breakthrough marks substantial progress, researchers note that understanding and manipulating solid-phase crystallization kinetics of thermally evaporated perovskites remains crucial for further improvements. The complex process control required when using multiple precursors continues to present challenges for co-evaporation and hybrid methods.

The successful implementation of this reverse deposition approach reportedly opens new pathways for developing highly efficient and stable fully thermally evaporated perovskite solar cells, potentially accelerating their commercial viability and integration with existing semiconductor manufacturing infrastructure.