Researchers at Empa, National University of Singapore (NUS) and Helmholtz Institute Erlangen-Nürnberg for Renewable Energy HI ERN have reported novel electrical and optical enhancement approaches to maximize the performance of perovskite front cells.
The team introduced new electrical and optical techniques, using methyldiammonium diiodide and adjusting the optical interference spectrum. This resulted in a record efficiency of 20.2% (21.8% by J-V scan) for a semi-transparent perovskite cell and 81.5% average near-infrared transmittance.
When paired with a CIS bottom cell, the tandem efficiency reached 29.9%. Techno-economic studies showed that these tandems could deliver close to 2,000 Wh/m2 daily for certain locations and offer competitive electricity costs, ranging from 3 to 5 USDcents/kWh within ±30° latitude.
The team explained that despite the ease of fabrication and no current matching constraint in mechanically stacked thin-film-based tandem solar cells, both electrical and optical losses still limit the performance of wide-band-gap perovskite semi-transparent solar cells in such tandem devices. The thin-film tandems using both perovskite and CuInSe2 (CIS) have not yet achieved optimal levels for commercial viability. The team addressed this issue in their recent work, by maximizing the performance of perovskite front cells.
