A Near‐Infrared Absorption Small Molecule Acceptor for High‐Performance Semitransparent and Colorful Binary and Ternary Organic Photovoltaics
Chun‐Kai Wang, Bing‐Huang Jiang, Jong‐Hong Lu, Ming‐Tsang Cheng, Ru‐Jong Jeng, Yuwei Lu, Chih‐Ping Chen, Ken‐Tsung Wong
Abstract
Abstract An acceptor–donor–acceptor (A–D–A)‐type non‐fullerene acceptor (NFA), PTTtID‐Cl, featuring thieno[3,2‐ b ]thieno[2′′′,3′′′:4′′,5′′]‐pyrrolo[2′′,3′′:4′,5′]thieno[2′,3′:4,5]thieno‐[2,3‐ d ]pyrrole (DTPTt) as the electron‐rich core and 2‐(5,6‐dichloro‐3‐oxo‐2,3‐dihydro‐1 H ‐inden‐1‐ylidene)malononitrile (ID‐Cl) as the peripheral electron‐deficient terminal group was synthesized and characterized. PTTtID‐Cl exhibited strong absorption in the range of 700–850 nm in CHCl 3 and redshifted absorption centered at 881 nm in a thin film. The near infrared (NIR)‐absorption of PTTtID‐Cl was combined with a low‐bandgap polymer donor (PTB7‐Th) to achieve binary and semitransparent organic photovoltaics (OPVs) with a power conversion efficiency (PCE) of 8.9 % and 7.7 % (with an average visible transmittance (AVT) of 16.7 %), respectively. A ternary device with a ratio of PM7/PTTtID‐Cl/IT‐4F=1:0.15:0.85 ( w / w ) achieved a short‐circuit current density of 19.46 mA cm −2 , an open‐circuit voltage of 0.87 V, and a fill factor of 71.2 %, giving a PCE of 12.0 %. In addition, by employing the Ag/ITO/Ag microcavity structure, semitransparent colorful binary organic photovoltaics (OPVs) with superior transparency of 27.9 % at 427 nm and 22.7 % at 536 nm for blue and green devices, respectively, were prepared. The semitransparent colorful devices based on the optimized ternary blend gave PCEs of 8.7 %, 8.4 %, and 9.1 % for blue, green, and red devices, respectively. These results indicate the promising potential of PTTtID‐Cl as a NIR‐absorption NFA for applications in semitransparent colorful binary and ternary OPVs.