Evaluating Thiophene Electron‐Donor Layers for the Rapid Assessment of Boron Subphthalocyanines as Electron Acceptors in Organic Photovoltaics: Solution or Vacuum Deposition?

Abstract

In this study, we consider the choice of a standard electron-donating material to be paired with boron subphthalocyanines (BsubPcs) to rapidly assess the viability of new BsubPc derivatives as electron-accepting materials within organic photovoltaic devices (OPVs). Specifically, we evaluate the effectiveness of solution-cast poly(3-hexylthiophene-2,5-diyl) (P3HT) as an electron donor paired with BsubPc derivatives relative to vacuum-deposited sexithiophene (α-6T). By using fullerene (C60 ), boron subphthalocyanine chloride (Cl-BsubPc), and hexachloro boron subphthalocyanine chloride (Cl-Cl6 BsubPc) as electron acceptors, we find that devices made with α-6T outperform those with P3HT. However, the two thiophene-based materials show the same performance trends. Given the preservation of these trends, we can recommend either option for assessing the potential of new BsubPc derivatives; P3HT as a solution-cast electron-donor layer or α-6T as a vacuum-deposited alternative.

Boron Subphthalocyanines and Silicon Phthalocyanines for Use as Active Materials in Organic Photovoltaics

“…Derivatization has also led to altering the HOMO and LUMO such that the BsubPc can act as an electron accepting material within OPVs. As a result, BsubPcs have been explored as a possible replacement for the more typical fullerene‐acceptor‐based devices . More recent studies have identified certain BsubPc derivatives that are soluble enough in organic solvents to be solution‐deposited into organic electronics allowing the device fabrication to be more scalable …”

“…The validity of using α‐6T to screen the OPV potential of new BsubPc derivatives as electron acceptors (Figure ) was evaluated by comparing the performance of Cl‐BsubPc, Cl‐Cl 6 BsubPc and C 60 . Results demonstrated that α‐6T is suitable as a standard electron donor to pair with BsubPc derivatives in vacuum deposited PHJ devices, with even α‐6T/Cl‐Cl 6 BsubPc outperforming α‐6T/C 60 despite significant V OC losses.…”

“…Several novel BsubPc derivatives were synthesized and paired with an α‐6T in subsequent studies . The ability to fine‐tune the V OC through peripheral chlorination was also demonstrated, although pairing α‐6T with BsubPcs with deep LUMO energy levels (Cl‐Cl 6 BsubPc, Cl‐Cl 12 BsubPc) substantially reduces the V OC and overall OPV performance.…”

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

“…P3HT:PC 61 BM BHJ OPV baseline devices performed according to literature [6] with a Jsc = 8.19 ± 0.43 mA•cm −2 , Voc = 0.56 ± 0.02 V and FF = 0.61 ± 0.04 resulting in an average power conversion efficiency (PCE) of 2.87% ± 0.21%. Our P3HT/C 60 PHJ OPV baseline devices also performed according to literature [21] with a Jsc = 2.58 ± 0.05 mA•cm −2 , Voc = 0.22 ± 0.01 V, FF = 0.48 ± 0.02, and PCE = 0.28 ± 0.02%. It should be noted that our devices have an area of 0.325 cm 2 , which is larger than other commonly reported devices in literature.…”

“…However, to the best of our knowledge, only one application of DPHJ devices with PC 71 BM has been reported using PCDTBT [20]. Only a few studies have explored the combination of a solution processed layer followed by the evaporation of C 60 resulting in a hybrid processed bilayer device [21,22]. Despite their good accepting abilities and their high electron mobility, fullerene derivatives only have a small absorption overlap with the solar spectrum, and their relatively small band gap limits the resulting device open-circuit voltage (Voc), which is directly related to the energy difference between the donor highest occupied molecular orbital (HOMO) and the acceptor lowest unoccupied molecular orbital (LUMO) [23][24][25].…”