Perovskite solar cells (PSCs) have become a revolutionary photovoltaic technology because of their high performance, low cost, and easy fabrication of large-scale flexible devices. However, the solution processing and the low formation energy of perovskites lead to numerous defects formed at both the bulk and interfaces of the perovskite layer, which ultimately results in a substantial deficit in the open-circuit voltage (VOC).

In a study published in Angewandte Chemie, Prof. LU Linfeng from Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences, collaborated with Prof. Alex K.-Y. Jen at City University of Hong Kong reported a facile and effective strategy for precisely modulating the perovskite by incorporating AlOx deposited by atomic layer deposition (ALD) on the top interface.

Researchers found that Al3+ ions not only infiltrated in the perovskite layer but also interacted with halide ions. The modification contributed to realizing better-matched energy levels, suppressed ion migration and minimized interfacial carrier losses simultaneously.

Additionally, the self-encapsulation effect of this dense interlayer could inhibit volatile ion overflow at high temperatures and improve light and thermal stability.

Consequently, the ALD-AlOx modification could significantly improve the PCE of wide-bandgap PSCs from 19.32% to 21.80%. More importantly, a monolithic perovskite-silicon tandem solar cells using AlOx-modified perovskite achieved a PCE of 28.50% with good stability.

The resulting 1.55-eV PSC and module also achieved a PCE of 25.08% (0.04 cm2) and 21.01% (aperture area of 15.5 cm2), respectively, proving the universality of the strategy.

 The study provides an effective way for efficient and stable wide-band gap perovskite and perovskite-silicon TSCs and shed light on large-area inverted PSCs.

Figure:The schematic diagram of incorporating AlOx deposited on perovskite surface(image by SARI)