Improved performance for polymer solar cells using CTAB-modified MoO3 as an anode buffer layer

We report a method to prepare molybdenum oxide thin films using the stable cetrimonium bromide-modified MoO 3 (CTAB-modified MoO 3 ) precursor solution . The effect of thermal treatment on the optical, crystalline, morphologic properties and surface wettability is greatly obvious because of the pyrolytic decomposition of CTAB. The highly efficient and stable polymer solar cells (PSCs) have been also fabricated by adopting CTAB-modified MoO 3 nanocomposite films as the novel and universal anode buffer layers (ABLs). The P3HT:ICBA based solar cells with CTAB-modified MoO 3 at 200   °C heat treatment exhibit an best power conversion efficiency (PCE) of 5.80% with long-term stability, and the PTB7:PC 71 BM based solar cells with CTAB-modified MoO 3 at 200   °C heat treatment show an best PCE of 8.34% with long-term stability, which are higher than that of the corresponding devices with PEDOT:PSS films. The improvement in device performance is mainly due to the agreeable electrical properties and enhanced charge extraction of the CTAB-modified MoO 3 ABLs, and CTAB modification to the MoO 3 surface can effectively passivate its surface traps, suppress the recombination loss of carriers. The surface of CTAB-modified MoO 3 films is also more hydrophobic than that of the PEDOT:PSS. In a word, these indicate the CTAB-modified MoO 3 films may be used as a novel and generally applicable hole transport layer for high-efficiency and ambient stable polymer solar cells.