Controlling Doping Concentration of Metal Nanoparticles for Enhanced Performance in <scp>NFA</scp>‐Based Organic Solar Cell

ABSTRACT Nanostructured metals have been employed as an important ingredient to enhance performance in photonic devices. It has attracted special interest in thin‐film organic solar cells (TFOSCs) as a mechanism to improve photon capture using thin solar absorber. Potassium sulphide doped with silver (K 2 S/Ag) was synthesized with the view to have core shell like structures nanoparticle (NP). The particles were then incorporated into solar absorber layer of TFOSCs at different concentrations. Nonfullerene acceptor (NFA)‐based solar cells were fabricated, in an inverted device structure, using an active layer composed of donor polymer poly‐(4,8‐bis(5‐(2‐ethylhexyl) thiophene‐2‐yl)benzo[1,2‐b; 4,5‐ b ′]‐dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluoro‐thieno [3,4,b]‐thiophene‐)‐2‐carboxylate‐2‐6‐diyl) (PTB7‐Th), and nonfullerene (NFA), 3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)‐indanone))‐5,5,11,11‐tetrakis(5‐hexyl‐thienyl)‐dithieno[2,3‐d:2′,3′‐ d ′]‐ s ‐indaceno[1,2‐b:5,6‐ b ′]dithiophene (ITIC‐Th). This study reveals the importance of the optimal percolation threshold for efficient charge transport in NFA‐based TFOSC. The highest performance was achieved at 1% concentration with a PCE as high as 10.51%, of 23.74 mA/cm 2 , and FF of 58.86% compared to the reference cell. Such results indicate that the measured electrical and optical properties of the K 2 S/Ag metal NPs doped polymer films demonstrated augmented characteristics for photon energy harvesting. The study highlights the importance controlling concentrations as it is evident from device performances.