Resent Progress in Side-Chain Engineering of Organic Photovoltaic Conjugated Polymer

Abstract

Photovoltaic conjugated polymer materials are composed of π-conjugated backbone and flexible side chains. Their potential advantages of cost-effective production, fabrication on flexible and light weight substrates by roll-to-roll solution processing, capability to be fabricated into flexible devices and reduced environment impact have made them receive considerable attention in both academia and industry. In recent years, most of the interest has been directed into the optimization of main chain, while research on side-chain engineering of polymer is relatively few. Initially, side chains have been primarily utilized as solubilizing groups in organic photovoltaic conjugated polymers. However, roles which side chains play are far beyond. Accordingly, it has been found that side chains of organic conjugated polymer have a different impact on polymer absorption, emission, energy level, carrier mobility, nanoscale morphology and interfacial contact. Certainly enough, these findings have profound guiding significance on molecular structure design and optimization, blend microstructure, interfacial morphology, preparation methods and processing technology of device and so on. Moreover, based on ameliorative preparation and processing technology of device, side-chain engineering is deserved to be deeply researched due to their remarkably improved ability to regulate and control blend microstructure, interfacial morphology so as to obtain ideal photovoltaic properties and device performance, the ultimate goal. Thus, as for resent progress in application, in this perspective article, we will present a review on side chain engineering and assess different side chain on the basis of molecular structure design and optimization, as well as summarize relevant issues to be solved and related work in our laboratory.

Cyclopentadithiophene based branched polymer electrets synthesized by friedel–crafts polymerization

“…The more hydrophobic property of P1 than P2 is because of P1 containing alkyl chain while P2 containing alkoxyl chain. Alkyl chain exhibits more hydrophobic property than alkoxyl chain . The transfer, gate leakage current and output characteristics of the OFET memories are shown in Supporting Information Figures S17 and S18, and the initial threshold voltages ( V Th ) of P1 and P2‐based OFET memories are observed of −6.4 and 3.6 V with ON/OFF current ratios ( I ON / I OFF ) of 8.4 × 10 4 and 1.0 × 10 3 , respectively.…”

Effects of alkyl side chain length of low bandgap naphtho[1,2‐c:5,6‐c′]bis[1,2,5]thiadiazole‐based copolymers on the optoelectronic properties of polymer solar cells

“…In fact, the roles which these side chains play are far beyond. And side chains have a significant impact on absorption, emission, energy level, aggregation, carrier mobility, morphology, interfacial contact, crystallinity, molecular orientation, dielectric constant ( ɛ r ) of polymers, and their PV properties . The key to select the side chain needs to make the balance between polymer solubility and the self‐assembly ability inducing polymer backbone from disordered to ordered.…”

“…And side chains have a significant impact on absorption, emission, energy level, aggregation, carrier mobility, morphology, interfacial contact, crystallinity, molecular orientation, dielectric constant (E r ) of polymers, and their PV properties. 9,16,[30][31][32][33][34][35][36] The key to select the side chain needs to make the balance between polymer solubility and the self-assembly ability inducing polymer backbone from disordered to ordered. Early in 2005, Causin et al studied the effect of the different alkyl length in poly(3-alkylthiophene)s, and demonstrated the longer side chain would decrease the interaction, hole mobility, and absorbance.…”

Engineering the self-assembly of diketopyrrolopyrrole-based molecular semiconductors via an aliphatic linker strategy

“…In contrast, routes for controlling molecular self-assembly by engineering the solubilizing side chains can preserve the electronics of the semiconducting core. 31 This route has been widely investigated for π-conjugated polymers, [32][33][34][35][36][37][38] and to lesser extent for small molecule organic semiconductors. [39][40][41][42] Indeed, since the selfassembly of a typical molecular semiconductor with standard aliphatic solubilizing chains is dominated by π-π interactions, side chain engineering offers limited control.…”