Wang Chenglai, Jing Yuancheng, Chen Liying, Xiong Wei
Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, MC 0358, La Jolla, California 92093-0358, United States.
Material Science and Engineering Program, University of California, San Diego, 9500 Gilman Drive, MC 0418, La Jolla, California 92093-0418, United States.
J Phys Chem Lett. 2022 Sep 22;13(37):8733-8739. doi: 10.1021/acs.jpclett.2c02130. Epub 2022 Sep 12.
Direct charge transfer at wet-processed organic/organic heterojunction interfaces is observed using femtosecond interfacial sensitive spectroscopy. UV-vis absorption and ultraviolet photoelectron spectroscopy both indicate that a new interfacial energy gap (∼1.2 eV) exists when an interface is formed between regioregular poly(3-hexylthiophene-2,5-diyl) and poly(benzimidazobenzophenanthroline). Resonant pumping at 1.2 eV creates an electric field-induced second-order optical signal, suggesting the existence of a transient electric field due to separated electrons and holes at interfaces, which recombine through a nongeminate process. The fact that direct charge transfer exists at wet-processed organic/organic heterojunctions provides a physical foundation for the previously reported ground-state charge transfer phenomenon. Also, it creates new opportunities to better control charge transfer with preserved momentum and spins at organic material interfaces for spintronic applications.
利用飞秒界面敏感光谱观察到了湿处理有机/有机异质结界面处的直接电荷转移。紫外-可见吸收光谱和紫外光电子能谱均表明,当在区域规整的聚(3-己基噻吩-2,5-二亚基)和聚(苯并咪唑并苯并菲咯啉)之间形成界面时,会存在一个新的界面能隙(约1.2电子伏特)。在1.2电子伏特处的共振泵浦产生了电场诱导的二阶光信号,这表明由于界面处分离的电子和空穴而存在瞬态电场,它们通过非简并过程复合。湿处理有机/有机异质结处存在直接电荷转移这一事实为先前报道的基态电荷转移现象提供了物理基础。此外,它为在自旋电子学应用中更好地控制有机材料界面处具有保留动量和自旋的电荷转移创造了新机会。