Carrier Conduction Characteristics in P3HT: PCBM Bulk Heterojunction Structures Under Sunlight Illumination

Injection properties of electrons and holes at the interface of electrodes/active layer for blending poly(3-hexylthiophene) (P3HT) and methanofullerene [6,6]-phenyl–C61–butyric acid methyl ester (PCBM) based on structures of Au/MoO3/P3HT: PCBM/ MoO3/Au as hole dominated device and Al alloy/P3HT: PCBM/Al alloy as electron dominated device were investigated. Both of hole and electron injections were ascribed to Schottky thermionic emission mechanism. The barrier height of carrier injection was estimated under a simulated air mass (AM) 1.5G spectrum illumination and dark conditions, respectively. The interfacial state at Al alloys/ P3HT: PCBM interface was estimated to be 1.4 × 1014 states/cm2/eV under illumination by extrapolating the relation of electron barrier heights and work functions using different Al alloys.