50 °C low-temperature ALD SnO2 driven by H2O2 for efficient perovskite and perovskite/silicon tandem solar cells

Although perovskite solar cells (PSCs) based on SnO2 have reached a power conversion efficiency (PCE) over 25%, large-scale fabrication remains the main obstacle to the commercialization of PSCs. Therefore, considering the process compatibility, low-temperature processing and large-area fabrication technologies have received widespread attention as those are ideal for upscaling of single and tandem devices. Herein, we demonstrated an effective atomic layer deposition (ALD) process by using H2O2 as an oxygen source and the deposition temperatures can be lowered up to 50 °C due to the high activity of H2O2. The low temperature deposition enables conformal coverage of the substrate and results in a pinhole-free film with high optical transmittance, excellent electron extraction properties, and large area uniformity. Notably, a high PCE of 20.70% is achieved for single junction PSCs based on ALD-SnO2 (50 °C). When the ALD-SnO2 applied to p-i-n structure perovskite/silicon heterojunction tandem solar cell, an efficiency of 26.67% was obtained. The results demonstrate the potential of the low-temperature ALD processed metal oxide for large-scale manufacturing of optoelectronic devices with competitive performances.