An Extremely Narrow‐Band‐Gap Conjugated Polymer with Heterocyclic Backbone and its Use in Optoelectronic Devices

Abstract

A novel narrow-band-gap conjugated polymer with heterocyclic backbone, poly[4,7-bis(4-decanyl-2-thienyl)-2 0 ,1 0 ,3 0 -benzothiadiazole-thiophene-2,5-] (PDDBT, E g ¼ 1.38 eV) was synthesized by a Stille coupling reaction. Prototype bulk heterojunction photovoltaic cells from PDDBT and [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) with a ITO/ PEDOT:PSS/PDDBT:PCBM(1:3)/Ba/Al device architecture showed power conversion efficiencies up to 0.13% under AM1.5 solar simulator (100 mW Á cm À2 ) with an open-circuit voltage V oc of 0.65 V, a short-circuit current density J sc of 0.6 mA Á cm À2 , and a photocurrent response up to 880 nm. The electroluminescent device from PDDBT showed a near-infrared light emission peak at around 830 nm with maximal external quantum efficiency of 0.08% and a turn-on voltage at 3.5 V.Normalized PL and EL spectra of PDDBT and photosensitivity of PVCs based on PDDBT/PCBM (1:3) blend. The scheme shows the chemical structure of PDDBT.

The synthesis and properties of novel π-conjugated 2,1,3-benzothiadiazole oligomers

“…MS (EI) m/z: 300. Elemental analysis, calculated for C 12 H 15 BrN 2 S: C, 48.17%; H, 5.05%; N,9.36%;S,10.72%;Br,26.70%. Found: C,48.35%;H,5.06%;N,9.57%;S,10.84%;Br,26.75%.…”

“…Elemental analysis, calculated for C 18 H 18 N 4 S 2 : C, 60. 99%;H,5.12%;N,15.80%;S,18.09%. Found: C,61.14%;H,5.28%;N,15.77%;S,18.31%.…”

Copolymers of Cyclopentadithiophene and Electron‐Deficient Aromatic Units Designed for Photovoltaic Applications

“…[2,3] New materials that are able to convert a larger fraction of the solar spectrum have contributed significantly to improving the energy conversion efficiency. [2,[4][5][6][7][8][9][10][11][12][13][14] The main strategy to control the band gap of conjugated polymers is incorporating electron-rich (donors) and electron-poor groups (acceptors) in an alternating fashion in the main chain of the polymer. [15] The energy conversion efficiency of a photovoltaic cell is set by the product of short-circuit current density (J sc ), fill factor (FF), and open-circuit voltage (V oc ) relative to the light intensity.…”

Recent Advances in P-Type Conjugated Polymers for High-Performance Solar Cells

“…Thus, although forming the alternating arrangement of D (Th 2 ) and A (BT) along the conjugated backbone, the bulkiness of alkyl side chains disrupted the coplanarity of poly(Th 2 -alt-BT), and resulted in copolymers with E g similar or even larger to that of P3HT. To obtain Th x /BT-based copolymers with both good solubility and lower E g , researchers applied the synthetic strategy of copolymerizing the Th 2 BT with thiophene and bithophene to afford P4 and P5 [50,51]. Both P4 and P5 are soluble in common solvents.…”