Integrated Effects of Two Additives on the Enhanced Performance of PTB7:PC71BM Polymer Solar Cells

Abstract

Organic photovoltaics (OPVs) are fabricated with blended active layers of poly [[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]thiophenediyl]]: [6,6]-phenylC71-butyric acid methyl ester (PTB7:PC71BM). The active layers are prepared in chlorobenzene (CB) added different additives of 1, 8-Diiodooctane (DIO) and polystyrene (PS) with different concentrations by spin coating. A small addition, 0.5%–5% by weight relative to the BHJ components, of inert high molecular weight PS is used to increase the solution viscosity and film thickness without sacrificing desirable phase separation and structural order. The effects of the PS are studied with respect of photovoltaic parameters such as fill factor, short circuit current density, and power conversion efficiency. Together with DIO, the device with 3.0 v% DIO and 1 wt % PS shows a high power conversion efficiency (PCE) of 8.92% along with an open-circuit voltage (Voc) of 0.76 V, a short-circuit current (Jsc) of 16.37 mA/cm2, and a fill factor (FF) of 71.68%. The absorption and surface morphology of the active layers are investigated by UV-visible spectroscopy, atomic force microscopy (AFM) respectively. The positive effect of DIO and PS additives on the performance of the OPVs is attributed to the increased absorption and the charge carrier transport and collection.

Structure and Charge Transport Anisotropy of Polythieno[3,4‐b]‐Thiophene‐co‐Benzodithiophene (PTB7) Oriented by High‐Temperature Rubbing

“…29 A film thickness of 15±5nm was determined from the absorbance at 695 nm and reference data from the literature. 30 For GIXD experiments, PTB7 films were prepared on Si(100) wafers (Silchem). After cleaning the substrates and UV-Ozone treatment, the films were deposited by doctorblading a 5 wt % solution in CF at 53°C.…”

Investigations of Novel High-Temperature Resistant Polymers for Electro-Optical Applications in Signal Processing Systems

“…The main chain includes the diphenylquinoxaline moiety connected by ether bridges. Both the phenyl and the ether group contribute to the good solubility and to the excellent film forming properties of this polymer [16].…”

Influence of pH-neutral lithium polystyrenesulfonate polyelectrolyte on the energy band structure and performance of organic solar cells

“…Bulk heterojunction active layer solutions were prepared one night before and allowed to stir at 45 °C on a hot plate over-night. PTB7: [6,6]-Phenyl-C71-butyric acid methyl ester (PC71BM) solutions (1:1.5 ratio) were prepared in chlorobenzene solvent with a 3% DIO additive 36 . These were spin-coated on top of the HTLs at 1300 rpm for 45 seconds and dried for 10 minutes on a hot plate at 80 °C.…”

“…PTB7 : [6,6]-phenyl-C71-butyric acid methyl ester (PC 71 BM) solutions (1 : 1.5 ratio) were prepared in chlorobenzene solvent with a 3% DIO additive. 36 These were spin-coated on top of the HTLs at 1300 rpm for 45 seconds and dried for 10 minutes on a hot plate at 80 1C. Then, ETLs comprising poly(9,9-bis(3 0 -(N,N-dimethyl)-N-ethylammonium-propyl-2,7fluorene)-alt-2,7-(9,9-dioctylfluorene))dibromide (PFN + Br À ) (Sigma, 0.1 wt%) were deposited using solutions in methanol solvent and spin-coated at 2000 rpm for 40 seconds.…”