title: Accessing the Triplet State in Heavy-Atom-Free Perylene Diimides.
abstract: Previous studies of perylenediimides (PDIs) mostly utilized the lowest singlet excited state S1 . Generation of a triplet excited state (T1 ) in PDIs is important for applications ranging from photodynamic therapy to photovoltaics; however, it remains a formidable task. Herein, we developed a heavy-atom-free strategy to prompt the T1 ←S1 intersystem crossing (ISC) by introducing electron-donating aryl (Ar) groups at the head positions of an electron-deficient perylenediimide (PDI) core. We found that the ISC efficiency increases from 8 to 54 % and then to 86 % by increasing the electron-donating ability of head-substituted aryl groups from phenyl (p-PDI) to methoxyphenyl (MeO-PDI) and then to methylthioxyphenyl (MeS-PDI). By enhancing the intramolecular charge-transfer (ICT) interaction from p-PDI to MeO-PDI, and then to MeS-PDI, singlet oxygen generation via energy-transfer reactions from T1 of PDIs to (3)O2 was demonstrated with the highest yield of up to 80 %. These results provide guidelines for developing new triplet-generating PDIs and related rylene diimides for optoelectronic applications.
authors: Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.|Graduate University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
authors: Zhenyi
authors: Z
authors: Yu
authors: Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China. yswu@iccas.ac.cn.
authors: Yishi
authors: Y
authors: Wu
authors: Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
authors: Qian
authors: Q
authors: Peng
authors: Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
authors: Chunlin
authors: C
authors: Sun
authors: Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.|Graduate University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
authors: Jianwei
authors: J
authors: Chen
authors: Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.|Beijing Key Laboratory for Optical Materials and Photonic Devices Department of Chemistry Capital Normal University, Beijing, 100048, P.R. China.|Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, P. R. China.
authors: Jiannian
authors: J
authors: Yao
authors: Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China. hongbing.fu@iccas.ac.cn.|Beijing Key Laboratory for Optical Materials and Photonic Devices Department of Chemistry Capital Normal University, Beijing, 100048, P.R. China. hongbing.fu@iccas.ac.cn.|Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, P. R. China. hongbing.fu@iccas.ac.cn.
authors: Hongbing
authors: http://orcid.org/0000-0003-4528-189X
authors: H
authors: Fu
keywords: charge transfer; intersystem crossing; perylene diimide; singlet oxygen generation; triplet excited state