- 标题
- 摘要
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- 实验方案
- 产品
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A 3D nonfullerene electron acceptor with a 9,9a?2-bicarbazole backbone for high-efficiency organic solar cells
摘要： One-dimensional ladder-type nonfullerene electron acceptors (NFAs) with large fused ring cores have been widely used in highly efficient organic solar cells (OSCs). Recent studies have demonstrated that small molecule acceptors with three-dimensional (3D) structures may exhibit low energy loss, and hence can lead to improved OSC performance. In this study, a new 3D NFA (99CZ-8F) with a 9,9'-bicarbazole backbone was designed, synthesized, and characterized, where two linear A-D-A architectures were linked by a single N-N bond. 99CZ-8F showed strong absorption in the range of 500-800 nm in the solid state, which is complementary to the absorption of the donor material PM6. After regulating the morphology of the active layer via binary solvent mixture, the optimized device exhibited a maximum power conversion efficiency (PCE) of 6.6 – 0.1 %, which is among the best reported values for 3D nonfullerene electron acceptor based OSCs.
关键词： Organic solar cells,end-capped groups,3D molecular structure,bicarbazole,nonfullerene electron acceptor
更新于2025-09-23 15:19:57
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Forming a metal-free oxidatively-coupled agent, bicarbazole, as a defect passivation for HTM and an interfacial layer in a p-i-n perovskite solar cell exhibits nearly 20% efficiency
摘要： In this study we synthesized three simple and inexpensive (34–120 USD/g) 3,3′-bicarbazole–based hole transporting materials (BC-HTMs; NP-BC, NBP-BC and PNP-BC) through a metal-free oxidative coupling, in excellent yields (≥ 95%). These bicarbazoles contain phenylene or biphenylene substituents on the carbazole N atom, with extended π-conjugation achieved through phenylene units at the 6,6′-positions of the bicarbazole. When using NBP-BC as a dopant-free HTM in a p–i–n perovskite solar cell (PSC), we achieved a power conversion efficiency (PCE) of 13.04% under AM 1.5G conditions (100 mW cm–2); this PCE was comparable with that obtained when using PEDOT:PSS as the HTM (12.67%). BC-HTMs showed the large grain size (μm) of perovskite than PEDOT:PSS-based, due to defect passiviation on indium tin oxide (ITO) substrate and good hydrophobicity. Furthermore, we realized highly efficient and stable PSCs when using the p–i–n device structure ITO/NiOx/NP-BC/perovskite/PC61BM/BCP/Ag. The bifacial defect passivation effect of the interfacial layer improved the grain size of the perovskite layer and also enhanced the performance; the best performance of the NiOx/NP-BC device was characterized by a short-circuit current density (Jsc) of 22.38 mA cm–2, an open-circuit voltage (Voc) of 1.09 V, and a fill factor (FF) of 79.9%, corresponding to an overall PCE of almost 20%. This device structure has competitive potential because its performance is comparable with that of the record high efficiency PSCs. Under an Ar atmosphere, the PCE of the NiOx/NP-BC PSC device decayed by only 4.55% after 168 h; it retained 90.80% of its original PCE after 1000 h. A morphological study revealed that the films of the BC-HTMs were indeed smooth and hydrophobic, and that the perovskite films spin-coated upon them were uniform and featured large grains (micrometer scale). Time-resolved photoluminescence (TRPL) spectra of the perovskite films suggested that the hole extraction capabilities of the NiOx/BC-HTMs were better than that of the bare NiOx. The superior film morphologies of the NiOx/BC-HTMs were responsible for the performances of their devices being comparable with those of bare NiOx-based PSCs.
关键词： power conversion efficiency,3,3′-bicarbazole,perovskite solar cells,hole transporting materials,metal-free oxidative coupling,dopant-free
更新于2025-09-16 10:30:52