Researchers at imec and University of Hasselt at Energyville, Belgium, recently set out to improve two key perovskite interfaces for solar cells for efficiency and lifetime.
The work focusses on the upper interface between the perovskite and the fullerene-C60 electron transport layer and the lower interface between the perovskite and the NiOx-based hole transport layer.
To enhance efficiency, both interfaces were treated with an ammonium salt, specifically 2-thiopheneethylammonium chloride (TEACl). The results were compared to perovskite cells with untreated layers and is expected to increase performance by creating a 2D perovskite layer at the interface.
This resulted in a conversion efficiency of 24.3% for the dual-interface-treated solar cells, along with a short-circuit density of 24.5 mA/cm2, an open-circuit voltage of 1.17 V, and a fill factor of 84.6 percent.
“Besides the increase in efficiency, we also observed a remarkable stability,” said Tom Aernouts, R&D manager of the Thin-Film Photovoltaics team.
After 1,000 hours of continuous operation under one-sun illumination, the perovskite cells retained 97% of its performance. After 1,850 hours of aging, dual-layer-treated cells retained 88% of their initial performance, compared to 55% in non-treated cells. Combined, these results demonstrate extraordinary operational and thermal stability of the treated PSCs. Next to cell-level optimizations, researchers also examined further upscaling to a mini-module with an active area of 3.63 cm2.
“Our research group aims not only to develop more efficient but also scalable PSCs, paving the way for commercialization. Therefore, at the PV cell production level, materials and processes are chosen and evaluated based on these future perspectives,” he said.
For a module design, the process achieved efficiency of 22.6% and a fill factor of 82.4%, indicating excellent reproducibility.
“Since dual interface modulations have shown effectiveness in different perovskite compositions, these findings further contribute to the development of scalable and commercially viable perovskite solar cell technology,” he added.