Unveiling Charge Carrier Dynamics at Organic-Inorganic S-Scheme Heterojunction Interfaces: Insights From Advanced EPR

• Published in: Advanced materials (Weinheim) 2024-12, p.e2414803
• Main Authors: Gu, Miaoli, Zhang, Jianjun, Kurganskii, Ivan V, Poryvaev, Artem S, Fedin, Matvey V, Cheng, Bei, Yu, Jiaguo, Zhang, Liuyang
• Format: Article
• Language: English
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.202414803

Understanding charge carrier transfer at heterojunction interfaces is critical for advancing solar energy conversion technologies. This study utilizes continuous wave (CW), pulse, and time-resolved (TR) electron paramagnetic resonance (EPR) spectroscopy to explore the radical species formed at the TAPA (tris(4-aminophenyl)amine)-PDA (Terephthaldicarboxaldehyde)/ZnIn S (TP/ZIS) heterojunction interface. CW and pulse EPR identify stable radical defects localized near the interface, accessible to water molecules. Time-resolved EPR reveals a photoinduced electron transfer from TP to ZIS, leading to the generation of spin-correlated radical pairs under light irradiation, signifying efficient charge carrier separation and spatial transfer within the S-scheme heterojunction. This electron transfer mechanism, confirmed through in situ X-ray photoelectron spectroscopy and femtosecond transient absorption spectroscopy, suppresses undesirable carrier recombination, extending charge carrier lifetimes. These findings provide novel insights into the transport direction of charge carriers at the S-scheme heterojunction interface, offering valuable guidance for designing highly efficient and stable organic-inorganic heterojunction photocatalysts for solar energy applications.