Organic Solar Cell with an Active Area > 1 cm² Achieving 15.8% Certified Efficiency using Optimized VIS‐NIR Antireflection Coating

Organic solar cells are on the verge of reaching 20% power conversion efficiency (PCE) on small device areas (< 0.1 cm 2 ). Herein, an improved efficiency of organic solar cells based on the donor polymer D18 combined with the non‐fullerene acceptor Y6 with an active area of ≥1 cm 2 reaching a certified PCE of 15.8% is reported. This is achieved due to an increase in photogenerated current enabled by a fully magnetron sputtered multilayer antireflection coating (ARC) custom designed for the absorption profile of the photoactive layer. The influence of this ARC in the visible to near infrared range is quantified by means of full optical device simulations predicting a photogenerated current gain of 3.9%. With the advanced device architecture, the best solar cell is measured independently by Fraunhofer ISE calibration lab obtaining the following values: open‐circuit voltage = 851.3 mV, short‐circuit current density = 25.11 mA cm −2 , fill factor = 73.89% on an active area of 1.0645 cm 2 thus yielding the improved world record efficiency in the category of cell areas ≥1 cm 2 .