Highly efficient bulk heterojunction photovoltaic cell based on tris[4-(5-phenylthiophen-2-yl)phenyl]amine and C70 combined with optimized electron transport layer

Abstract

Efficient bulk heterojunction (BHJ) photovoltaic cells (PVs) based on 5 wt. % donors and C70 were fabricated. Tris[4-(5-phenylthiophen-2-yl)phenyl]-amine (TPTPA)-based BHJ PVs show higher power conversion efficiency (ηPCE) than aluminum phthalocyanine chloride-based BHJ PVs. Although the absorption of AlPcCl is complementary to that of C70, TPTPA's high hole mobility and symmetrical molecular structure are likely to be crucial contributing factors to the higher ηPCE. Phase separation occurs in the 5%-TPTPA blend. The device was optimized via replacement of the bathocuproine buffer by a combination of 3,4,9,10-perylenetetracarboxylic bis-benzimidazole and bathocuproine. ηPCE of 5.96% is achieved because of the decreased series resistance.

Efficient small molecule-based bulk heterojunction photovoltaic cells with reduced exciton quenching in fullerene

“…A PCE of 5.65% has been achieved in the DBP and C 70 -based BHJ cell with MoO 3 buffer, which is in consist with previously reported results [6,15]. Compared with the BHJ cell using MoO 3 buffer, the BHJ cell with PEDOT: PSS buffer exhibits a significantly enhanced J sc ($12.50 mA/cm 2 ), which corresponds to the improvement of EQE response at the mid-wavelength range, where C 70 has a strong absorption coefficient (from 450 to 550 nm).…”

“…C 70 exhibits two intense absorption bands in the whole visible wavelength range, while the absorption of DBP is strong in the wavelength range from 500 to 600 nm. The blend active layer in the DBP and C 70 -based BHJ cells is set to 60 nm thickness with the ratio of 1:9, based on many reports on such BHJ systems [5][6][7]14,15]. Therefore, C 70 in the blend active layer contributes to most of the absorption in the wavelength range from 300 to 700 nm and DBP only covers a part of the absorption in the wavelength range from 500 to 600 nm.…”

“…In recent years, high power conversion efficiencies (PCEs) have been achieved by developing bulk heterojunction (BHJ) small molecule-based OPV cells with low donor concentration in a fullerene matrix via either thermal evaporation or solution processes [1][2][3][4][5][6][7]. The bulk heterojunction structure comprising a uniformly distributed donor/acceptor (D/A) blend active layer is beneficial for efficient exciton dissociation at the D/A interface [1][2][3][8][9][10][11].…”

Thiophene dendrimer-based low donor content solar cells

“…However, elucidation of the exact mechanism is complex and will require further study. 24 The use of MoOx instead of PEDOT:PSS, as an anode interlayer, has been shown to yield an increase in efficiency for low donor content devices, 3,6,7,11,25 and hence in the final aspect of this study, we prepared devices of the following structure: ITO/MoOx/42T:PCBM/Ca/Al (with the BHJ formed from a 13 mol. % casting solution), with and without methanol vapor annealing.…”

“…However, there have been a number of recent reports of moderately efficient donor:fullerene solar cells in which the weight percent of the donor is significantly lower (a few percent). A small range of non-polymeric donors including 4,4 0 -cyclohexylidenebis[N,N-bis(4-methylphenyl)benzenamine] (TAPC), 3 a spiro-bifluorene modified perylene diimide, 4 a dinaphthothienothiophene, 5 tris[4-(5-phenylthien-2-yl)phenyl]-amine, 6 a tetraphenyldibenzoperiflanthene, 7 a spirothioxanthene, 8 a chlorido-indium phthalocyanine, 9 and a spirofluorene (SF8TBT), 10 as well as poly(3-n-hexylthiophene) (P3HT) 11 have been investigated with either C60 (for evaporated devices) or PC70BM (for solution processed cells). Such devices can have a large and similar open-circuit voltage (%1.0 V) independent of the choice of donor, provided that molybdenum oxide (MoOx) is used as the hole extraction contact.…”