High‐Efficiency All‐Small‐Molecule Organic Solar Cells Based on an Organic Molecule Donor with Alkylsilyl‐Thienyl Conjugated Side Chains. Issue 27 (21st May 2018) - Bin, Haijun
Abstract: Two medium‐bandgap p‐type organic small moleculesH21 andH22 with an alkylsily‐thienyl conjugated side chain on benzo[1, 2‐ b :4, 5‐ b ′]dithiophene central units are synthesized and used as donors in all‐small‐molecule organic solar cells (SM‐OSCs) with a narrow‐bandgap n‐type small molecule 2, 2′‐((2Z, 2′Z)‐((4, 4, 9, 9‐tetrahexyl‐4, 9‐dihydro‐ s ‐indaceno[1, 2‐ b :5, 6‐ b ′]dithiophene‐2, 7‐diyl)bis(methanylylidene))bis(3‐oxo‐2, 3‐dihydro‐1H‐indene‐2, 1‐diylidene))dimalononitrile (IDIC) as the acceptor. In comparison toH21 with 3‐ethyl rhodanine as the terminal group, H22 with cyanoacetic acid esters as the terminal group shows blueshifted absorption, higher charge‐carrier mobility and better 3D charge pathway in blend films. The power conversion efficiency (PCE) of the SM‐OSCs based on H22:IDIC reaches 10.29% with a higher open‐circuit voltage of 0.942 V and a higher fill factor of 71.15%. The PCE of 10.29% is among the top efficiencies of nonfullerene SM‐OSCs reported in the literature to date. Abstract : High‐efficiency (10.29%) all‐small‐molecule organic solar cells are demonstrated based on an acceptor–donor–acceptor‐structured 2D conjugated organic molecule with an alkylsilyl‐thienyl conjugated side chain and cyanoacetic acid ester terminal groups as the donor and a narrow‐bandgap n‐type organic semiconductor, IDIC, as the acceptor.