Synthesis and photovoltaic properties of amorphous polymers based on dithienylbenzothiadiazole‐triphenylamine with hexyl side chains on different positions of thienyl groups

Abstract

We synthesized and characterized three new amorphous dithienylbenzothiadiazole (TBT)‐triphenylamine (TPA) polymers for application in bulk‐heterojunction (BHJ) organic photovoltaic (OPV) cells. Poly(3HTBT‐TPA) has hexyl side chains on the thienyl groups (pointing toward the benzothiadiazole (BTD) unit), and poly(4HTBT‐TPA) has hexyl side chains on the thienyl groups (pointing outward from the BTD unit). The incident photon to current conversion efficiencies (IPCEs) in the region from 550 to 650 nm for the OPV cells prepared using poly(4HTBT‐TPA) were higher than those for the OPV cells prepared using poly(3HTBT‐TPA) because the absorption spectrum for the poly(4HTBT‐TPA) has a slightly red‐shifted absorption edge. We also demonstrated that the poly(4HTBT‐TPA)‐based OPV performance is independent of the fabrication process, so using an amorphous film to fabricate BHJ OPV cells offers great advantages over using a polycrystalline film in terms of the high reproducibility of the OPV performance. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2536–2544

Synthesis of triarylamine-based alternating copolymers for polymeric solar cell

“…Since interpenetrating polymer-PCBM networks with a smaller domain size is known to be better for efficient charge transfer and separation, we ascribe that formation of the more uniform phase separated blend by thermal annealing leads to improvement of J sc , FF, and PCE [66,67]. PDNPADTBT-PC 70 BM solar cell showed improved V oc and J sc values compared to previously reported copolymers composed of triphenylamine and DTBT derivatives supporting our approach to obtain high performance PSCs [36,40,41].…”

“…Intriguingly, the copolymers exhibited low HOMO levels, which allow PSCs to have high V oc [63]. Compared with previous polymer systems composed of electron-rich triphenylamine and electron-deficient BT derivatives, such low HOMO levels of copolymers may be originated from the naphthalene unit introduced into the triarylamine [36,41,44,45].…”

Bulk Heterojunction Photovoltaic Cells with Triphenylamine-Based Amorphous Polymer and Non-Halogenated Solvent Processing Provide Reproducible Performance

“…A solution of poly(3HTBT-TPA):PC 70 BM (1:4, weight ratio) blend was subsequently spin-coated onto the PEDOT:PSS surface, forming a BHJ layer. This weight ratio of 1:4 is the optimum weight ratio for high performance, as reported in our previous paper [15]. The solvents used in this study were o-DCB, 1,2,4-trimethylbenzene (TMB), and 1,2-dimethylbenzene (o-xylene).…”

“…BHJ films fabricated using various solvents and annealed at different temperatures were studied in detail using UV-vis spectroscopy and atomic force microscopy (AFM). An amorphous polymer, poly(3HTBT-TPA), which consists of benzothiadiazole and triarylamine units, was prepared according to methods described in the literature [15]. The chemical structure of poly(3HTBT-TPA) is shown in Fig.…”

Synthesis and characterization of naphtho[2,1-b:3,4-b′]dithiophene-based polymers with extended π-conjugation systems for use in bulk heterojunction polymer solar cells

“…For example, alternating conjugated polymers may be obtained using D‐D or D‐A pairs with distinct electronic structures (D: electron–donor, A: electron–acceptor) along the polymer backbone. The push–pull interactions introduced by each moiety can be used to reduce the energy absorption band by improving the efficiency of intramolecular charge transfer (ICT) . Other strategies for improving the molecular design and obtaining high‐performance polymers involve the construction of strong π–π stacking interactions between polymer backbones to facilitate effective charge carrier transport .…”