Polymer heterojunction photodiodes with MEHPPV doped with organic acceptors

A series of commercial organic acceptors were blended into MEHPPV and photovoltaic parameters of the resulting polymer heterojunction photodiodes were tested. Photosensitivity of PV devices was improved when LUMO levels of acceptors are close to that of the C₆₀. The photoresponse can be further enhanced by substitution of a long alkyl chain in the polar acceptor molecules. For device with 1,2-decanoxyanthraquinone doped MEHPPV as an active layer, the photosensitivity at zero bias is increased to 0.00047 A/W from 0.00012 A/W for unsubstiluted acceptor. At voltage of -30V the photosensitivity reaches 0.15A/W, the same level as for device from MEHPPV-PCBM. We tentatively attribute such significant enhancement to the field-dependent mobility increase.