Nankai University’s Yongsheng Chen in EES: 17.33% at 13.5 cm²! A large conjugated rigid dimeric acceptor boosts power conversion efficiency beyond 20%!

Non-fullerene acceptors with a large conjugated rigid backbone facilitate reduced disorder and lower non-radiative recombination losses (ΔEnr), thereby enhancing the open-circuit voltage (Voc) of organic solar cells (OSCs). _OC ). However, due to the excessive aggregation of these receptors, an unfavorable active-layer morphology often forms, leading to a short-circuit current density (J _SC ) and a lower fill factor (FF), thereby significantly reducing device efficiency.

Based on this, Chen Yongsheng, Wan Xiangjian, Li Chenxi, and others from Nankai University A dimeric receptor, QD-1, is reported to possess a large conjugated rigid backbone, exhibiting low energetic disorder, small reorganization energy, and weakened electro-optical coupling—features that collectively contribute to reducing ΔEnr and enhancing charge mobility. Benefiting from the aforementioned advantages and the favorable fibrous morphology, binary organic solar cells based on PM6:QD-1 exhibit V _OC , J _SC and exhibits high and balanced device parameters compared with FF, thereby Achieved 19.46% This represents the highest power conversion efficiency (PCE) reported to date in binary organic solar cells employing a dimeric acceptor. By incorporating QD-1 into the PM6:BTP-eC9 blend, a remarkable PCE of 20.19% was achieved, with all three photovoltaic parameters improved thanks to optimized active-layer morphology. Furthermore, a 13.5 cm² module based on this ternary system delivered a high PCE of 17.33%. This paper was recently published in the journal under the title “A Large Conjugated Rigid Dimer Acceptor Enables 20.19% Efficiency in Organic Solar Cells.” Energy & Environmental Science Up.

In summary, the authors have designed a novel dimeric receptor, QD-1, characterized by a large, conjugated, rigid backbone. This dimeric receptor exhibits low reorganization energy, low energetic disorder, and weak electron–photon coupling. Leveraging these advantages and the well-defined fibrous morphology of the blended thin film, binary OSCs based on PM6:QD-1 achieved a power conversion efficiency (PCE) of 19.46%, representing the highest PCE reported to date for binary devices employing a dimeric acceptor. Notably, when QD-1 was incorporated into the PM6:BTP-eC9 blend, the resulting ternary device delivered a PCE of 20.19% and exhibited enhanced thermal stability. This improvement is attributed to enhanced exciton dissociation, reduced charge recombination and non-radiative recombination losses (ΔEnr), as well as higher charge carrier mobility compared with binary devices. Furthermore, compared with binary devices, ternary organic solar cells exhibit lower trap-state density and a more optimized morphology, leading to an increase in power conversion efficiency (PCE) while simultaneously improving open-circuit voltage (Voc), short-circuit current density (Jsc), and fill factor (FF). Ultimately, a large-area module with an active area of 13.5 cm² was fabricated, achieving a high power conversion efficiency (PCE) of 17.33%, which places it at the forefront among large-area modules. Our work demonstrates the remarkable potential of large-conjugated, rigid dimeric acceptors in achieving high-efficiency and high-stability organic solar cells, and will inspire further innovative exploration of the application of such large-conjugated, rigid backbones in OSCs.

Device Fabrication

Device structure:

ITO/2PACz/active layer/PNDIT-F3N/Ag

1. Wash the ITO glass thoroughly, treat with ozone for 15 minutes, spin-coat 2PACz at 3000 rpm for 20 seconds, and then anneal at 100°C for 5 minutes;

2. Total concentration: 13.2 mg/mL PM6: QD-1 (1:1.2 w/w) + 0.3% DIO dissolved in CF; PM6: BTP-eC9 (1:1.2 w/w); PM6: BTP-eC9: QD-1 (1:1:0.2). Add 80 wt% TCB (based on the combined mass of D and A) dissolved in CF, stir at room temperature overnight, spin-coat at 1800 rpm for 30 s, and anneal at 100°C for 5 min.

3. Spin-coat at 3,000 rpm for 20 seconds using a PNDIT-F3N solution in MeOH at 1 mg/mL with 0.5% v/v glacial acetic acid.

4. Evaporate 150 nm of Ag.

Module Structure:

glass/ITO/PEDOT:PSS/PM6:BTP-eC9:QD-1/PNDIT-F3N/Ag

1. Wash the ITO glass thoroughly, treat with ozone for 15 minutes, spin-coat PEDOT:PSS at 4300 rpm for 20 seconds, and then anneal at 160°C for 15 minutes;

2. The other steps are consistent with the above.