Enhanced power conversion efficiency of inverted organic solar cells by using solution processed Sn-doped TiO2 as an electron transport layer

We have investigated the photovoltaic properties of inverted solar cells comprising a bulk heterojunction film of thieno[3,4-b]-thiophene/benzodithiophene (PTB7) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM), sandwiched between indium tin oxide (ITO)/Sn-doped TiO2 front and MoO3/aluminum back electrodes. The inverted organic solar cell (IOSC) fabricated with a Sn-doped TiO2 film showed a significantly greater power conversion efficiency of 7.59%, compared to that of the TiO2 film (6.70%). Further studies confirm that the improved morphology and electrical properties of the Sn-doped TiO2 film result in reduced shunt loss and interfacial charge recombination and hence enhanced photovoltaic performance.