Synthesis and characterization of indenofluorene‐based copolymers containing 2,5‐bis(2‐thienyl)‐N‐arylpyrrole for bulk heterojunction solar cells and polymer light‐emitting diodes

Abstract

Two novel alternating p-conjugated copolymers, poly [2,8-(6,6 0 ,12,12 0 -tetraoctyl-6,12-dihydroindeno-[1,2b]fluorenealt-5(1-(2,6-diisopropylphenyl)-2,5-di(2-thienyl)pyrrole) (P1) and poly [2,8-(6,6 0 ,12,12 0 -tetraoctyl-6,12-dihydroindeno-[1,2b]fluorenealt-5(1-(p-octylphenyl)-2,5-di(2-thienyl)pyrrole) (P2), were synthesized via the Suzuki coupling method and their optoelectronic properties were investigated. The resulting polymers P1 and P2 were completely soluble in various common organic solvents and their weight-average molecular weights (M w ) were 5.66 Â 10 4 (polydispersity: 1.97) and 2.13Â 10 4 (polydispersity: 1.54), respectively. Bulk heterojunction (BHJ) solar cells were fabricated in ITO/PEDOT:PSS/polymer:PC 70 BM(1:5)/TiO x /Al configurations. The BHJ solar cell with P1:PC 70 BM (1:5) has a power conversion efficiency (PCE) of 1.12% (J sc ¼ 3.39 mA/cm 2 , V oc ¼ 0.67 V, FF ¼ 49.31%), measured using AM 1.5 G solar sim-ulator at 100 mW/cm 2 light illumination. We fabricated polymer light-emitting diodes (PLEDs) in ITO/PEDOT:PSS/emitting polymer:polyethylene glycol (PEG)/Ba/Al configurations. The electroluminescence (EL) maxima of the fabricated PLEDs varied from 526 nm to 556 nm depending on the ratio of the polymer to PEG. The turn-on voltages of the PLEDs were in the range of 3-8 V depending on the ratio of the polymer to PEG, and the maximum brightness and luminance efficiency were 2103 cd/m 2 and 0.37 cd/A at 12 V, respectively. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: [3169][3170][3171][3172][3173][3174][3175][3176][3177] 2010

Synthesis and photovoltaic properties of 1-(2,6-diisopropylphenyl)-2,5-di(2-thienyl)pyrrole-based low-bandgap polymers

“…In our laboratory, we have been interested in the preparation of 1-(2,6-diisopropylphenyl)-2,5-di(2-thienyl)pyrrole (N-aryl TPT)-based p-conjugated polymers for BHJ solar cell applications [37][38][39][40]. Previously reported alternating copolymer containing N-aryl TPT unit and indenofluorene (PTPTIF) was found to show narrow absorption band in the range of 350-520 nm, and the photovoltaic studies showed maximum PCE of 1.12 % with J sc of 3.39 mA cm -2 , V oc of 0.67 V, FF of 49.31 % [37].…”

Influence of the Electron Acceptor Group on the Backbone of N-(2,6-Diisopropylphenyl)-2,5-di(2-thienyl)pyrrole-Based Polymer

“…The optical band gap of polymer PIFTPCNT was calculated from the onset wavelength of the optical absorption as thin film to be 2.40 eV, which is slightly higher than that of the reported polymer PIFTPT band gap. 9 The strong electron acceptor group on the polymer backbone of PIFTPCNT was found to induce the blue shift in the absorption maximum and broaden the absorption band quite significantly compared to the absorption of PIFTPT as shown in Figure 2.…”

“…[2][3][4][5][6][7][8] In our laboratory, we have been interested in preparing N-(2,6-diisopropylphenyl)-2,5-di(2-thienyl)pyrrole (N-aryl TPT)-based π-conjugated polymers as electron donor materials for PSC applications. Recently, we reported several N-aryl TPT-based polymers containing electron rich units such as indenofluorene (PIFTPT), 9 2,5-dioctyloxyphenylene (PPTPT), 10 3-octylthiophene (PTTPT), 10 and electron deficient units such as thiophene-benzothiadiazolethiophene (PTPTTBT), 11 benzothiadiazole (PTPTIFB and TPyTBz), 12,13 and thiadiazoloquinoxaline (TPyTDzQ) 14 for PSC applications. The N-aryl TPT-based donor (D) polymers showed maximum energy conversion efficiency of 1.35%, 10 whereas the donor-acceptor (D-A) and donor-acceptor-donor (D-A-D) polymers showed maximum PCE of 1.57%.…”

A Novel Donor-Acceptor-Acceptor-Acceptor Polymer Containing Benzodithiophene and Benzimidazole-Benzothiadiazole-Benzimidazole for PSCs

“…21,22 On the other hand, the LUMO energy level of PBDTBBB was calculated to be −2.84 eV from HOMO energy level and optical band gap values by using the equation LUMO = HOMO+E g . 29,30 The HOMO and LUMO levels of PBDTBBB indicate that its HOMO energy level is deep enough to get reasonalble V oc and the LUMO level is positioned well above the LUMO level of the acceptor (PC 71 BM), which ensures the possibility of the efficient electron transfer from the polymer to PC 71 BM. 31,32 In this instance, the synthesized polymer PBDTBBB might be suitable for PSCs application.…”