A Bifunctional Copolymer Additive to Utilize Photoenergy Transfer and To Improve Hole Mobility for Organic Ternary Bulk-Heterojunction Solar Cell

Abstract

To realize the high efficiency organic photovoltaics (OPVs), two critical requirements have to be fulfilled: (1) increasing the photon energy absorption range of the active layer, and (2) improving charge separation and transport in the active layer. This study reports the utilization of THC8, a novel fluorescence-based polymer containing propeller-shaped di-triarylamine and fluorene moieties in the active layer consisting of poly-3-hexylthiophene and [6,6]-phenyl-C61-butyric acid methyl ester to form a ternary bulk heterojunction. The results showed that the high absorbance and strong fluorescence of THC8 at 420 and 510 nm, respectively, broadened the spectral absorption of the OPV, possibly through Förster resonance energy transfer. In addition, the morphology of the device active layer was improved with the addition of a suitable amount of THC8. Consequently, the charge transport property of the active layer was improved. The best power conversion efficiency (PCE) of the device with THC8 was 3.88%, a 25% increase compared to the PCE of a pristine OPV.

High-Performance Small Molecule/Polymer Ternary Organic Solar Cells Based on a Layer-By-Layer Process

“…27,[34][35][36][37][38] And such third component should exhibit the complementary absorption spectrum with the binary to extend the absorption of the solar spectrum and suitable energy level for exciton dissociation and charge carrier extraction. [39][40][41][42] Currently the ternary blend OSCs base on polymer as the host donor have drawn much attention, [43][44][45][46][47][48] and the efficiency has exceeded 8% using polymer or small molecule as complementary donor. 36,40,[49][50] In the ternary blend OSC, the morphology of the blend active layer is also one of critical parameters, which was similar to the binary blend OSC.…”

Improvement of Stability for Small Molecule Organic Solar Cells by Suppressing the Trap Mediated Recombination

“…[1][2][3][4][5][6][7][8][9] Although the power conversion efficiency (PCE) has been improved greatly in the last decade, the short lifetime of OSCs hinders the residential application. It is generally accepted that the device performance degrades fast when it is exposed to oxygen and/or humid environment.…”

Effect of Acceptor Strength on Optical and Electronic Properties in Conjugated Polymers for Solar Applications

“…For effective charge carrier generation by exciton dissociation at the interface between the donor polymer and fullerene, the offset between the LUMO of the donor polymer and LUMO of fullerene acceptor must be at least 0.30 V [38][39][40]. However, it has been found recently that good charge separation in the donor polymer reduces the offset required for effective charge transfer from the donor polymer to the fullerene in a BHJ system 18,41,42. In a study by Carsten et al18 , the transient absorption results of blended films of PTB7 with fullerenes showed a fast excitonic state decay of less than 120 fs while blends of PTBF2 and PBB3 with fullerenes showed longer excitonic decay times of 19 ps and 190 ps respectively.…”