Synthesis of New Indolocarbazole-Acceptor Alternating Conjugated Copolymers and Their Applications to Thin Film Transistors and Photovoltaic Cells

Abstract

We report synthesis, properties, and optoelectronic device characteristics of six new indolocarbazole-acceptor conjugated copolymers prepared by Suzuki coupling reaction. Two different linkages of indolocarbazole (28IC and 39IC) and four acceptors of 2,3-didodecylthieno [3,4-b]pyrazine (TP12), 2,3-bis(4-(2-ethylhexyloxy) phenyl)thieno [3,4-b]pyrazine (TPO), 2,1,3-benzothiadiazole (BT), and 2,3-bis(4-(2-ethylhexyloxy)phenyl)quinoxaline (QO) were used to explore the effects of acceptor structure, linkage, and side group on the electronic and optoelectronic properties. The optical band gap (eV) of the studied copolymers were in the following order: P28IC-TPO (1.58) < P39IC-TP12 (1.79) < P28IC-TP12 (1.84) < P28IC-BT (2.09) < P28IC-QO (2.31) < P39IC-QO (2.34). The hole mobility and on-off ratios of the studied copolymers were in the ranges 1.66 × 10 -5 to 4 × 10 -4 cm 2 /V • s and 40-46900, respectively. It basically depended on the degree of intromolecular charge transfer between indolocarbazole and acceptor as well as the HOMO level. The power conversion efficiency (PCE) of the indolocarbazole-acceptor polymer/PC 61 BM or PC 71 BM based photovoltaic cells were in the range 0.14-1.40% under the illumination of AM 1.5G (100 mW/cm 2 ). P28IC-QO showed the best PCE among the studied copolymers because of its suitable HOMO/LUMO energy level, high molecular weight, good hole mobility, efficient PL quenching, and large V oc .

Synthesis of New Thiadiazole-Containing Polythiophene Derivatives and Their Application to Organic Solar Cells

“…Bulk-heterojunction (BHJ) polymer solar cells (PSCs), in which the photoactive layer consists of an interpenetrating network of a donor (D) of π-conjugated polymer and an acceptor (A) of soluble fullerene, have attracted much attention because of their easy processability, low material cost, high efficiency, and mechanical flexibility [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. One of the most successful system until now utilizes a blend of P3HT and [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) as the active layer, normally giving PCEs in the range of 4-5% [2,6,7].…”

Highly Luminous Sky-Blue Organic Light-Emitting Diodes Based on the Bis[(1,2)(5,6)]indoloanthracene Emissive Layer

“…12 Tuning of indolocarbazole properties may be performed through a formal extension of the π-conjugation by attaching aromatic moieties to the basic polycyclic frame. 13,14,15,16,17,18 Finally, indolocarbazoles have been used as monomer units in either homo- 19,20 or copolymers -the latter used as active components in FETs 21,22 or OPVs. 23,24,25,26,27,28 Reports on more π-extended polycyclic aromatic compounds bearing carbazole units are less frequent.…”

Synthesis and Characterization of New Dihydroindolo[3,2-b]indole and 5,6-Bis(octyloxy)-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole-Based Polymer for Bulk Heterojunction Polymer Solar Cells

“…[13][14][15] A precise and thorough investigation is required to gain deep insight into the structural features of fused π-conjugated systems, which can excel the photovoltaic performance.…”