China's perovskite-silicon tandem solar cell hits 33.35% efficiency

A Chinese company, Longi, has achieved a world record power conversion efficiency (PCE) of 33.35% for a flexible perovskite-silicon tandem solar cell, certified by the US National Renewable Energy Laboratory (NREL). This marks the first internationally recognized record for a flexible crystalline silicon-perovskite tandem solar cell, highlighting its potential for commercial use in lightweight and flexible photovoltaic applications such as space and vehicle-integrated solar power. The tandem cell is built on a 60-micron-thick ultra-thin silicon bottom cell and demonstrates high efficiency on both small (1 cm²) and wafer-sized (260 cm²) areas, with a power-per-weight ratio of up to 1.77 W/g. The breakthrough relies on a dual-buffer-layer strategy that enhances interfacial adhesion and mitigates damage during manufacturing, while preserving efficient charge extraction. This involves a bilayer of tin oxide (SnOx) deposited via atomic layer deposition and chemical vapor deposition to