High-efficiency organic solar cells with low voltage-loss of 0.46 V

The recent evolution of active components yielded brilliant progresses for organic solar cells(OSCs),yet the mechanism is needed to be clearly understood.In this wo rk,two electron acceptors,a linear SN6-2Br and a V-shaped BTP-2Br,are developed with nitrogen atoms introduced to replace the traditional sp3-hybridized carbon in the fused ring.BTP-2Br possesses an electron-de ficient central core,which exhibits slightly blue-shifted absorption as well as deepened HOMO-level compared with SN6-2Br.The corresponding photovoltaic performance from V-shaped BTP-2Br based devices exhibit superior performance especially in short-circuit current(Jsc),despite an enhanced absorption and charge carrier mobilities for SN6-2Br.The primary reason for the higher JSC from BTP-2Br is faster exciton diffusion and dissociation in ble nds,than those of SN6-2Br.As a result,PBDB-TF:BTP-2Br based devices achieve a power conversion efficiency(PCE)of 13.84%with an voltage-loss of only 0.46 V,which is one of the lowest values ever reported.Moreover,we fabricated semitransparent OSCs that exhibit an excellent PCE of 9.62%with average visible transparency of 20.1%.