Melamine-Doped Cathode Interlayer Enables High-Efficiency Organic Solar Cells

Abstract

Charge transport, extraction, and collection play important roles in the working process of organic solar cells (OSCs), and the interface engineering is one of the key factors to realize the high-throughput printing fabrication of OSCs. The structure design or doping of electrode interlayer materials can effectively suppress the recombination of carriers at the interface and improve the ohmic contact between the active layer and the electrodes, which is a useful method to achieve a high power conversion efficiency (PCE). Poly­(9,9-bis­(3′-(N,N-dimethyl)-N-ethylammoniumpropyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene))­dibromide (PFN-Br) is a widely used alcohol-soluble cathode interlayer material. By doping PFN-Br with melamine (MA), the charge extraction efficiency and nongeminate recombination at the cathode interface are successfully optimized. Finally, the device efficiencies of PM6:Y6 and PM6:BTP-eC9 are increased to an amazing 17.44% and 18.58%, respectively. This work provides a new strategy for the fabrication of high-efficiency OSCs.

Tuning the Crystallinity and Phase Separation by Two‐Step Annealing Enables Block Copolymer‐Based Organic Solar Cells with 15% Efficiency

“…[24] The devices were fabricated based on the conventional structure of ITO/PEDOT:PSS-PA/block copolymer/PFN-Br-MA/Ag. [34,35] The current density versus voltage ( J-V ) curves are illustrated in Figure 1a, with corresponding parameters listed in Table 1. The best efficiency as high as 15.01% is gained by applying 20 s chloroform (CF) vapor treatment before 100 °C TA, which mainly improves the J SC and FF compared with the one-step annealing device.…”

Perylene‐diimide‐based cathode interlayer materials for high performance organic solar cells

“…Particularly, the doping effect is often utilized to improve the electrical conductivity of the cathode interlayer, including self-doping of the CIMs or with added dopant. 52,53 The doping effect is usually detected by the electron spin resonance (ESR) spectrum, 54 which is a technique for studying chemical species that have one or more unpaired electrons, such as organic and inorganic free radicals or inorganic complexes possessing a transition metal ion. For the study of CIMs, an ESR signal of organic free radicals stands for the electron transfer process in CIMs or between CIMs and acceptors in the active layer.…”

Efficient semi-transparent organic solar cells enabled by a quasi-heterojunction active layer structure

“…10–13 Donor:acceptor blend bulk heterojunctions (BHJs) fabricated via one-step processing are the most prevalent active layer structures in opaque OSCs and ST-OSCs. 14–18 Due to the rapid development of novel organic donor and acceptor materials, the power conversion efficiencies (PCEs) of opaque BHJ OSCs have broken through 18%. 19–24 The BHJ layer requires that the donor and acceptor are blended in a suitable ratio and form nanoscale phase separation for efficient exciton dissociation and charge collection, in which it is difficult to adjust the absorption of the donor and acceptor independently.…”