High fabrication yield organic tandem photovoltaics combining vacuum- and solution-processed subcells with 15% efficiency

Abstract

Multijunction solar cells are effective for increasing the power conversion efficiency beyond that of single-junction cells. Indeed, the highest solar cell efficiencies have been achieved using two or more subcells to adequately cover the solar spectrum. However, the efficiencies of organic multijunction solar cells are ultimately limited by the lack of high-performance, near-infrared absorbing organic subcells within the stack. Here, we demonstrate a tandem cell with an efficiency of 15.0 ± 0.3% (for 2 mm2 cells) that combines a solution-processed non-fullerene-acceptor-based infrared absorbing subcell on a visible-absorbing fullerene-based subcell grown by vacuum thermal evaporation. The hydrophilic–hydrophobic interface within the charge-recombination zone that connects the two subcells leads to >95% fabrication yield among more than 130 devices, and with areas up to 1 cm2. The ability to stack solution-based on vapour-deposited cells provides significant flexibility in design over the current, all-vapour-deposited multijunction structures. Organic tandem solar cells combining solution- and vapour-deposited layers are difficult to fabricate due to the degradation of the underlying subcell during the deposition of the next subcell. Here, Che et al. design a charge recombination layer that protects the underlying cell and leads to 15% average PCE for 2 mm2 devices and 11.5% PCE for 1 cm2 devices.