High-Efficiency Polymer Photovoltaic Devices With Glycerol-Modified Buffer Layer

The properties of organic photovoltaic devices (OPVs) with poly(3,4-ethylene dioxythiophene) : poly(styrene- sulfonate ) buffer layer modified by doping glycerol with different concentration have been investigated. The power conversion efficiency (PCE) of the device has been improved from 3.37% to 4.32% under AM 1.5 G (90 mW/cm ² illumination) after the buffer layer was modified. The short-circuit current density also 24% increased with the modification. Surprisingly, as the doping concentration of glycerol was more than 30 mg/ml, PCE of the OPVs no longer increased even though the conductivity of buffer layer continually increased with doping concentration of glycerol. We particularly analyzed the effect of glycerol-modified buffer layer on performance of polymer photovoltaic devices by the contact angle and atomic force microscopy measurements, and the influence of surface morphology of buffer layer was also discussed.