Interface Modification of Inverted Bulk Heterojunction Organic Solar Cell by ZnO and CuOx Layers

Abstract

The enhanced performance of the poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) bulk heterojunction devices was achieved by interface modification with solution processed ZnO and CuO x  interlayer. The highest power conversion efficiency (PCE) of  .24±0.01% was achieved by optimizing the thickness of the interface layers by varyingspin coating speeds. The thin CuO layer improved both the short circuit current density x 2 (12.23mA/cm ) and fill factor (0.62) by providing additional light absorption through redistributing the electric field within the active layer.
The incident photon to current conversion efficiency (IPCE) was also improved to 67% by a 15nm thick CuO x interlayer, showing that maximum carriers can be generated by optimizing the thickness of the amorphous CuO layer. x2 The fabricated devices were characterized under 100mW/cm illumination and optical properties of each layer were also investigated.