Most highly efficient small molecule-based bulk heterojunction (BHJ) photovoltaic cells contain a large
concentration of fullerene in their blend active layers. However, the excitons generated in fullerene
can seriously quench at the surface of the commonly used MoO3 buffer layer, becoming a key limitation
to the photovoltaic performance of these cells. In this study, we’ve investigated various anode buffer layers
in the thermally evaporated tetraphenyldibenzoperiflanthene (DBP) and C70-based BHJ cells with high
C70 concentration. It’s been found that obviously enhanced power conversion efficiency (PCE) of up to
6.26% can be obtained in DBP and C70-based BHJ cells via simply replacing the MoO3 buffer by poly(3,
4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS), which is also a commonly used anode
buffer material in polymer-based BHJ cells. Photoluminescence spectra results have confirmed the suppression
of exciton quenching at the anode interface by inserting this PEDOT: PSS buffer. Moreover, after
adding a C70 interlayer for better electron extraction and the further suppression of exciton quenching,
the DBP and C70-based M-i-n photovoltaic cells show a remarkable PCE of 7.04% under illumination with
100 mW/cm2, AM 1.5G simulated solar light.