Cathode modification of polymer solar cells by ultrahydrophobic polyelectrolyte

ABSTRACT

A ultrahydrophobic polylectrolyte (PVPy-F) based on poly(4-vinylpyridine) is applied to polymer solar cell (PSC) as a cathode buffer layer. The Kelvin probe microscopy measurement support the formation of favorable interface dipole between the active layer and the cathode. PSC with the PVPy-F as a cathode buffer layer demonstrate the power conversion efficiency (PCE) of 3.46% (open circuit voltage (V_oc) = 0.62 V, short circuit current (J_sc) = 10.8 mA/cm², fill factor (FF) = 51.7%), which is better than the device without interlayer (PCE = 2.88%, V_oc = 0.61 V, J_sc = 9.15 mA/cm², FF = 51.6%). This is due to that the reduction of a Schottky barrier at the cathode interface. Most increase in the PCE of the devices with interlayer is resulted from enhancement of the J_sc.

KEYWORDS:

• polymer solar cell
• cathode buffer layer
• electron collection layer
• ultrahydrophobic polyelectrolyte

Acknowledgments

This work was supported by a Research Grant of Pukyong National University (2015 year).