Infrared photocurrent spectral response from plastic solar cell with low-band-gap polyfluorene and fullerene derivative

Abstract

Plastic solar cells were fabricated using a low-band-gap alternating copolymer of fluorene and a donor–acceptor–donor moiety (APFO-Green1), blended with [6,6]-phenyl-C61-butyric acid methylester or 3′-(3,5-Bis-trifluoromethylphenyl)-1′-(4-nitrophenyl)pyrazolino[60]fullerene as electron acceptors. The polymer shows optical absorption in two wavelength ranges from 300<λ<500nm and 650<λ<1000nm. Devices based on APFO-Green1 blended with the later fullerene exhibit an outstanding photovoltaic behavior at the infrared range, where the external quantum efficiency is as high as 8.4% at 840nm and 7% at 900nm, while the onset of photogeneration is found at 1μm. A photocurrent density of 1.76mA∕cm2, open-circuit voltage of 0.54V, and power conversion efficiency of 0.3% are achieved under the illumination of AM1.5 (1000W∕m2) from a solar simulator.

Polymer‐Fullerene Bulk‐Heterojunction Solar Cells

“…Following Marcus theory, the rate of electron transfer in polarizable media is related to the driving force DG 0 (energy difference between the initial and the transferred state), which is related to the difference in the HOMO and LUMO energies. Although functional bulk-heterojunction composites with LUMO differences as low as 0.1 eV were reported, [117] we will use a value of 0.25 eV in the simulation. For the ii) polaron loss we will again assume a value of 0.25 eV.…”

“…The values for the inorganic semiconductors were taken from [119]. V oc values for the organic semiconductors were taken from the following publications: PCDTQX and PCDTBX [76], APFO Green-1 [117], and PSiF-DBT [75]. The arrow indicates the potential for higher V oc in case of a better-matched acceptor.…”

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.…”

Low-band gap poly(di-2-thienylthienopyrazine):fullerene solar cells

“…Reports on low-band gap polymers are emerging recently. [6][7][8][9][10][11] In designing low-band gap polymers for bulk heterojunctions solar cells various aspects need to be considered. For a conventional p-n junction solar cell with a single band gap ͑E g ͒, a reduction of E g results in an increased absorption of light but decreased open circuit voltage ͑V oc ͒.…”