Hole transport layer free bulk heterojunction organic solar cells with high work function ITO anodes

In this work, hole transport layer (HTL) free bulk heterojunction organic solar cells (BHJ-OSCs) based on PTB7:PCBM as active layer have been fabricated by employing various ITO anodes with different work function. The power conversion efficiency of the BHJ-OSCs is significantly improved from 3.76 to 8.47% with increasing the work function of the ITO anode. By combining Mott–Schottky curves, external quantum efficiency and reflectance spectra of the BHJ-OSCs, we identify that the improved optoelectronic conversion due to the enhanced built-in electric field within the active layer which is induced by the high work function ITO anodes. The hole transport layer free device structure can be considered for the fabrication of cost-effective BHJ-OSCs due to their simple structure and high efficiency.