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Highly Efficient Inverted Organic Solar Cells Through Material and Interfacial Engineering of Indacenodithieno[3,2‐ b ]thiophene‐Based Polymers and Devices
Author(s) -
Intemann Jeremy J.,
Yao Kai,
Li YongXi,
Yip HinLap,
Xu YunXiang,
Liang PoWei,
Chueh ChuChen,
Ding FeiZhi,
Yang Xi,
Li Xiaosong,
Chen Yiwang,
Jen Alex K.Y.
Publication year - 2014
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.201302426
Subject(s) - thiophene , materials science , energy conversion efficiency , polymer solar cell , organic solar cell , polymer , absorption (acoustics) , optoelectronics , photovoltaic system , acceptor , organic chemistry , composite material , chemistry , ecology , physics , biology , condensed matter physics
A synergistic approach combining new material design and interfacial engineering of devices is adopted to produce high efficiency inverted solar cells. Two new polymers, based on an indacenodithieno[3,2‐ b ]thiophene‐difluorobenzothiadiazole (PIDTT‐DFBT) donor–acceptor (D–A) polymer, are produced by incorporating either an alkyl thiophene (PIDTT‐DFBT‐T) or alkyl thieno[3,2‐b]thiophene (PIDTT‐DFBT‐TT) π‐bridge as spacer. Although the PIDTT‐DFBT‐TT polymer exhibits decreased absorption at longer wavelengths and increased absorption at higher energy wavelengths, it shows higher power conversion efficiencies in devices. In contrast, the thiophene bridged PIDTT‐DFBT‐T shows a similar change in its absorption spectrum, but its low molecular weight leads to reduced hole mobilities and performance in photovoltaic cells. Inverted solar cells based on PIDTT‐DFBT‐TT are explored by modifying the electron‐transporting ZnO layer with a fullerene self‐assembled monolayer and the MoO 3 hole‐transporting layer with graphene oxide. This leads to power conversion efficiencies as high as 7.3% in inverted cells. PIDTT‐DFBT‐TT's characteristic strong short wavelength absorption and high efficiency suggests it is a good candidate as a wide band gap material for tandem solar cells.