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Naphtho[1,2‐ c :5,6‐ c ′]bis[1,2,5]thiadiazole‐Containing π‐Conjugated Compound: Nonfullerene Electron Acceptor for Organic Photovoltaics
Author(s) -
Chatterjee Shreyam,
Ie Yutaka,
Karakawa Makoto,
Aso Yoshio
Publication year - 2016
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.201504153
Subject(s) - organic solar cell , homo/lumo , materials science , acceptor , conjugated system , fluorene , electron acceptor , energy conversion efficiency , band gap , photovoltaics , photochemistry , photovoltaic system , optoelectronics , polymer , molecule , organic chemistry , chemistry , physics , composite material , condensed matter physics , ecology , biology
The development of nonfullerene acceptor materials applicable to organic photovoltaics (OPVs) has attracted considerable attention for the achievement of a high power conversion efficiency (PCE) in recent years. However, it is still challenging due to the insufficiency of both the variety of effective electron‐deficient units and certain guidelines for the design of such materials. This work focusses on naphtho[1,2‐ c :5,6‐ c ′]bis[1,2,5]thiadiazole (NTz) as a key electron‐deficient unit. Therefore, a new electron‐accepting π‐conjugated compound (NTz‐Np), whose structure is based on the combination of NTz and the fluorene‐containing imide‐annelated terminal units (Np), is designed and synthesized. The NTz‐Np compound exhibits a narrow optical energy gap (1.73 eV), a proper energy level (−3.60 eV) of the lowest unoccupied molecular orbital, and moderate electron mobility (1.6 × 10 −5 cm 2 V −1 s −1 ), indicating that NTz‐Np has appropriate characteristics as an acceptor against poly(3‐hexylthiophene) (P3HT), a representative donor. OPV devices based on NTz‐Np under the blend with P3HT show high photovoltaic performance with a PCE of 2.81%, which is the highest class among the P3HT/nonfullerene‐based OPVs with the conventional device structure. This result indicates that NTz unit can be categorized as a potential electron‐deficient unit for the nonfullerene acceptors.