Synthesis and characterization of fused-thiophene containing naphthalene diimide n -type copolymers for organic thin film transistor and all-polymer solar cell applications

Abstract

Naphthalene diimide copolymers are attractive ntype materials due to their high electron affinities, high electron mobilities, and exceptional stability. Herein, we report a series of NDI-fused-thiophene based copolymers with each copolymer differing in the number of fused thiophenes in the donor monomer. Increasing the number of fused-thiophene moieties within an NDI-copolymer backbone is shown to not only enable tuning of the electronic structure but also improve charge mobilities within the active layer of organic field-effect transistors. Electron mobilities and on/off ratios as high as 0.012 cm 2 V 21 s -1 and I on / I off > 10 5 were measured from n-channel thin-film transistors fabricated using NDI-xfTh copolymers. Bulk heterojunction solar cell devices were also fabricated from the NDI-xfTh copolymer series in blends with poly(3-hexylthiophene) (P3HT) with PNDI-4fTh-based devices yielding the largest J sc (0.57 mA cm 22 ) and fill factor (55%) in addition to the highest measured PCE for this series (0.13%).

Development of Polymer Acceptors for Organic Photovoltaic Cells

“…The copolymers differed in terms of the number of thiophene rings in the fused thiophene systems, resulting in PNDI-2fTh (21), PNDI-3fTh (22), and PNDI-4fTh (23, Figure 4) [56]. The device fabricated with D1:23 showed the highest PCE of 0.13%, which was associated with the highest J SC (0.57 mA/cm 2 ) and FF (0.55) among the evaluated polymers.…”

Novel Approaches in the Design of Donor-Acceptor Oligomeric and Polymeric Materials for Photovoltaic Applications: D/A Blend versus Self-assembly of D/A by Covalent or Non-Covalent Interaction

“…By adding DIO as a solvent additive to optimize the mixing morphology of the P3HT: NDI-21 combination, the PCE and fill factor (FF) reached values of 1.63% and 0.66, respectively. Apartfrom this, several other NDI based donor-acceptor alternating polymers incorporating a variety of donors have been reported and implemented in solar cell devices; however their power conversion efficiencies were not very encourageable [79][80][81][82]. Zheng and co-workers reported three new building blocks of angular shaped NDI polymers as an acceptor with increasing number of thiophene as donor units (1-3) structure NDI-22.…”

A low band gap n-type polymer based on dithienosilole and naphthalene diimide for all-polymer solar cells application

“…Recently, the highest efficiency for PBDTTT-EF-T:N2200 all-PSCs is reported as 5.73% [33]. Other donor moieties in NDI-based polymer conclude fluorene [28], fused thiophenes [35], biselenophene [29,34,36], and so on.…”

“…The reported n-type polymers with a donor-acceptor structure incorporating cyano (CN) [11][12][13][14], 2,1,3-benzothiadiazole (BT) [15][16][17][18], diketopyrrolopyrrole (DPP) [19,20], thizaole [21], perylene diimide (PDI) [22][23][24][25], and naphthalene diimide (NDI) [18,[26][27][28][29][30][31][32][33][34][35][36] as the electron acceptor moiety are currently employed in all-PSCs. Among these materials, NDI-based conjugated polymers in particular have begun to attract significant attention as an expressly interesting class of acceptor materials due to their strong absortption in the visible range, relatively high electron mobility, solution-processability and air-stability.…”

“…Recently, the highest efficiency for PBDTTT-EF-T:N2200 all-PSCs is reported as 5.73% [33]. Other donor moieties in NDI-based polymer conclude fluorene [28], fused thiophenes [35], biselenophene [29,34,36], and so on.The bridged dithiophenes have specific advantages in constructing conjugated polymer [38]. In particular, dithienosilole (DTS), dithiophene unit bridged with an silicon atom (Si), has been found to possess better π-π stacking along the main chain of the polymers, high hole mobilities and strong light absorption in the visible region [38][39][40][41][42].…”