Investigation of Exciton Dissociation in Poly(9,9-dioctylfluorene-co-benzothiadiazole): 2,3,7,8,12,13,17,18-Octaethyl-21H,23H-Porphyrin Platinum (II) System for Photovoltaic Device Application

Exciton dissociation between a polyfluorene derivative, poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT), and a red phosphorescent dye, 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum (II) (PtOEP), has been investigated by photo-induced absorption (PIA) spectroscopy and photocurrent measurement of pristine F8BT and PtOEP blended F8BT film and devices. The PtOEP blended F8BT film shows a broad PIA spectrum centered at 780 nm (1.59 eV), which is spectrally different from those of pristine F8BT and PtOEP. In addition, the PtOEP blended F8BT photovoltaic device shows approximately a factor of two higher incident photon-to-current efficiency (IPCE) than the pristine F8BT photovoltaic device. The PIA and IPCE results firmly suggest that exciton dissociation efficiently takes place between F8BT and PtOEP in the PtOEP blended F8BT photovoltaic device.