Photocurrent spectroscopic studies of diketopyrrolopyrrole-based statistical copolymers

Moghe, Dhanashree and Dutta, GitishK and Patil, Satish and Guha, Suchi (2014) Photocurrent spectroscopic studies of diketopyrrolopyrrole-based statistical copolymers. In: PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 16 (9). pp. 4291-4298.

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Abstract

Diketopyrrolopyrrole (DPP) containing copolymers have gained a lot of interest in organic optoelectronics with great potential in organic photovoltaics. In this work, DPP based statistical copolymers, with slightly different bandgap energies and a varying fraction of donor-acceptor ratio are investigated using monochromatic photocurrent spectroscopy and Fourier-transform photocurrent spectroscopy (FTPS). The statistical copolymer with a lower DPP fraction, when blended with a fullerene derivative, shows the signature of an inter charge transfer complex state in photocurrent spectroscopy. Furthermore, the absorption spectrum of the blended sample with a lower DPP fraction is seen to change as a function of an external bias, qualitatively similar to the quantum confined Stark effect, from where we estimate the exciton binding energy. The statistical copolymer with a higher DPP fraction shows no signal of the inter charge transfer states and yields a higher external quantum efficiency in a photovoltaic structure. In order to gain insight into the origin of the observed charge transfer transitions, we present theoretical studies using density-functional theory and time-dependent density-functional theory for the two pristine DPP based statistical monomers.

Item Type:	Journal Article
Publication:	PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Publisher:	ROYAL SOC CHEMISTRY
Additional Information:	copyright for this article belongs to ROYAL SOC CHEMISTRY, ENGLAND
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	25 Mar 2014 09:39
Last Modified:	25 Mar 2014 09:39
URI:	http://eprints.iisc.ac.in/id/eprint/48648

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