Silicon Phthalocyanines as Acceptor Candidates in Mixed Solution/Evaporation Processed Planar Heterojunction Organic Photovoltaic Devices

Abstract

Silicon phthalocyanines (SiPc) are showing promise as both ternary additives and non-fullerene acceptors in organic photovoltaics (OPVs) as a result of their ease of synthesis, chemical stability and strong absorption. In this study, bis(3,4,5-trifluorophenoxy) silicon phthalocyanine ((345F)2-SiPc)) and bis(2,4,6-trifluorophenoxy) silicon phthalocyanine ((246F)2-SiPc)) are employed as acceptors in mixed solution/evaporation planar heterojunction (PHJ) devices. The donor layer, either poly(3-hexylthiophene) (P3HT) or poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT), was spin coated followed by the evaporation of the SiPc acceptor thin film. Several different donor/acceptor combinations were investigated in addition to investigations to determine the effect of film thickness on device performance. Finally, the effects of annealing, prior to SiPc deposition, after SiPc deposition, and during SiPc deposition were also investigated. The devices which performed the best were obtained using PCDTBT as the donor, with a 90 nm film of (345F)2-SiPc as the acceptor, followed by thermal annealing at 150 °C for 30 min of the entire mixed solution/evaporation device. An open-circuit voltage (Voc) of 0.88 V and a fill factor (FF) of 0.52 were achieved leading to devices that outperformed corresponding fullerene-based PHJ devices.

Layer-by-layer fabrication of organic photovoltaic devices: material selection and processing conditions

“…4, c19), which resulted in a V oc of 0.6 V. 87 A tetravalent silicon phthalocyanine (SiPc) functionalized in the axial position with fluorophenoxy groups ((246F) 2 /(345F) 2 -SiPc, Fig. 4, c20-21) was reported in bilayer cells as an acceptor by Faure et al 88 Bender and coworkers investigated boron subphthalocyanine (SubPc), 89 which consist of a bowl shaped macrocycle chelating a central boron atom, resulting in increased solubility and reduced propensity to aggregate. 90 Josey et al investigated axially-substituted chloro SubPc without and with peripheral chlorination (Cl-BSubPc, Cl-Cl 6 BSubPc, Fig.…”

“…62,63,66,68,72,73,75,77,78,83,84,86,87,[91][92][93][94][95][96][97][98][99][100][101][104][105][106][107][108]110,112,166,[194][195][196][197][198][199][200][201][202][203][204][205][206][207] Some examples of evaporated phthalocyanine-based NFAs have also been reported. 88,109,208 A summary of device performances and processing conditions from hybrid LbL OPVs prepared from thermally evaporated acceptors can be found in…”

Fluorinated Zinc and Copper Phthalocyanines as Efficient Third Components in Ternary Bulk Heterojunction Solar Cells

“…Different small molecules from phthalocyanine (Pc) derivatives have been described to provide alternative photovoltaic semiconductor materials for OSC applications. − Pcs play an important role as NFAs due to their high molar extinction coefficients, stability, and the highest occupied molecular orbital (HOMO)/lowest unoccupied molecular orbital (LUMO) energy levels complementary with the energy levels of the other two components. , However, Pcs have poor solubility in organic solvents and most of the Pcs used to date in ternary solar cells have been SiPcs thanks to the functionalization of the axial positions that avoid aggregation processes. − Due to this problem, to date, not too many Pcs have been incorporated in ternary solar cells. Different studies have been performed using CuPc and ZnPc as third components and in all of the cases resulted in an efficiency improvement compared to its two-component counterpart.…”

N-Type Solution-Processed Tin versus Silicon Phthalocyanines: A Comparison of Performance in Organic Thin-Film Transistors and in Organic Photovoltaics

“…While MPcs with divalent metal centers such as zinc and copper phthalocyanine (ZnPc and CuPc) have been widely reported as active materials in organic electronic devices, , MPcs with tetravalent metal centers, such as silicon and tin phthalocyanines (SiPcs and SnPcs), remain relatively unexplored. SiPcs and SnPcs have two axial bonds available for chemical modification, providing additional chemical handles to these materials, and facilitating tuning of their chemical and solid-state properties. ,− SiPcs have recently attracted significant interest as the active material in several emerging applications, such as organic light-emitting diodes (OLEDs), ,, organic photovoltaics (OPVs), − organic thin-film transistors (OTFTs), , photopolymerization, , and even photodynamic therapy. − SnPcs share many of the above listed attractive properties of SiPcs, with the added advantage of more facile and higher-yielding synthesis and purification, as illustrated in Figure , making them more desirable candidates for low-cost organic electronic devices. ,− , …”