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An Efficient Bulk‐Heterojunction Photovoltaic Cell Based on Energy Transfer in Graded‐Bandgap Polymers
Author(s) -
Gupta D.,
Kabra D.,
Kolishetti N.,
Ramakrishnan S.,
Narayan K. S.
Publication year - 2007
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200600183
Subject(s) - materials science , optoelectronics , photocurrent , band gap , energy conversion efficiency , polymer , acceptor , conjugated system , ternary operation , polymer solar cell , quantum efficiency , physics , computer science , composite material , programming language , condensed matter physics
It is demonstrated that the energy transfer from low‐conjugated (LC) poly[2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylene vinylene] (MEHPPV) to high‐conjugated (HC) MEHPPV, coupled with significant electron transfer from HC‐MEHPPV to an acceptor species, offers a viable route for an efficient photodiode over a wide spectral range. An enhanced incident‐photon‐to‐current conversion efficiency (IPCE) of 19 % over a wide spectral range and a power‐conversion efficiency (η P ) of 1 % (under monochromatic illumination at λ ∼ 530 nm and a power density of ca. 1 mW cm –2 ) are achieved in a ternary polymer‐blend film that consists of HC‐MEHPPV (low bandgap), LC‐MEHPPV (high bandgap), and an acceptor polymer, cyanoPPV (CNPPV), in an optimized ratio. The decisive role of the morphology that emerges during phase separation in the polymer blend is demonstrated by wide‐field photocurrent imaging.