Development of New Semiconducting Polymers for High Performance Solar Cells

Abstract

A new low band gap semiconducting polymer, PTB1, was synthesized and found promising for solar energy harvesting. Simple polymer solar cells based on PTB1 and methanofullerene [6,6]-phenyl-C(71)-butyric acid methyl esters (PC(71)BM) exhibit a solar conversion efficiency of 5.6%. An external quantum efficiency of 67% and fill-factor of 65% are achieved, both of which are among the highest values reported for a solar cell system based on a low band gap polymer.

Visible to Near-Infrared Light Harvesting in TiO2 Nanotube Array−P3HT Based Heterojunction Solar Cells

“…1,2 The fullerene acceptor absorbs very little light and is primarily used in blends to provide an efficient interface for exciton dissociation. Various efforts toward efficiency improvement in these devices are directed toward the development of low band gap polymers to absorb a broad swathe of the solar spectrum, [3][4][5][6] lowering the molecular energy levels of the semiconducting polymer to enhance the open circuit voltage of the organic solar cells, 1,7 and the control of the blended film morphology for enhanced exciton harvesting. [8][9][10][11][12] In the best performing solid-state dyesensitized solar cells (SS-DSSCs), η ∼ 5%, the only photon absorber is a dye, while the electron and hole transport functions are performed, respectively, by a disordered nanoparticulate TiO 2 network and a transparent small molecule spiro-OMeTAD.…”

“…Absorption, Emission, and Electrochemical Properties of SQ-1 Dye and P3HT Polymer 4 NPF 6 with a scan rate of 100 mV s -1 . c E 0-0 was determined from intersection of absorption and emission spectra in ethanol.…”

Incremental optimization in donor polymers for bulk heterojunction organic solar cells exhibiting high performance

“…1,21 Also, the authors demonstrated that the intermolecular ordering and, hence, the charge-carrier REVIEW mobility could be significantly improved upon substitution with fluorine atoms. 1,2,4,21,53 Similarly, several low band-gap polymers were reported using the electron-deficient TPD unit. 13,15,17,18,54 For example, Frechet et al reported polymers (P1-3) bearing BDT and TPD units with variable alkyl side chains attached to the TPD unit.…”

“…The introduction of strong electron acceptors into the polymer backbones impart a low HOMO level and hence a lower band gap of the polymers. 1,2,4 BT is one of the widely used electron-deficient units, 6,8,9 and recently several other electron-deficient moieties such as PyT, 11 thieno [3,4-c]pyrrole-4,6-dione (TPD), 13,17,18 NT, 7 and isoindigo 5 have been reported. In addition, fluorine-substituted BT, 12 TT, 1-4,21 and TAZ 13 have also been explored (Fig.…”

“…51,52 Yu et al developed BDT-based PTB1-7 polymers using the Stille coupling of alkoxy-substituted BDTs and ester-substituted TTs, which promoted the quinoid population and effectively reduced the band gap of the conjugated polymers. 1,2,4,21 The solubility of the polymers were greatly enhanced using branched alkyl side chains, and as a result, PTB2-7 exhibited better solubility in common organic solvents compared to PTB1 bearing linear alkyl side chains. 1,21 Also, the authors demonstrated that the intermolecular ordering and, hence, the charge-carrier REVIEW mobility could be significantly improved upon substitution with fluorine atoms.…”