13.6% Efficient Organic Dye-Sensitized Solar Cells by Minimizing Energy Losses of the Excited State

The electron-injection energy losses of dye-sensitized solar cells (DSSCs) are among the fundamental problems hindering their successful breakthrough application. Two triazatruxene (TAT)-based sensitizers, with one containing a flexible Z-type double bond and another a rigid single bond, coded as ZL001 and ZL003, respectively, have been synthesized and applied in DSSCs to probe the energy losses in the process of electron injection. Using time-resolved laser spectroscopic techniques in the kinetic study, ZL003 with the rigid single bond promotes much faster electron injection into the conductive band of TiO2 especially in the locally excited state (hot injection), which leads to higher electron density in TiO2 and a higher V-oc. The devices based on ZL003 exhibited a champion power conversion efficiency (PCE) of 13.6% with V-oc = 956 mV, J(sc) = 20.73 mA cm(-2), and FF = 68.5%, which are among the highest recorded results to date on single dye-sensitized DSSCs. An independent certified PCE of 12.4% has been obtained for devices based on ZL003.