Probe exciplex structure of highly efficient thermally activated delayed fluorescence organic light emitting diodes

• DOI: 10.1038/s41467-018-05527-4
• Publication Date: 2018-07-31T15:28:12Z
• Authors: Tzu-Chieh Lin; Monima Sarma; Yi-Ting Chen; Shih-Hung Liu; Ke-Ting Lin; Pin-Yi Chiang; Wei-Tsung Chuang; Yi-Chen Liu; Hsiu-Fu Hsu; Wen-Yi Hung; Wei-Chieh Tang; Ken-Tsung Wong; Pi-Tai Chou
• Keywords: Excimer; Acceptor; Chromophore

Abstract The lack of structural information impeded the access efficient luminescence for exciplex type thermally activated delayed fluorescence (TADF). We report here pump-probe Step-Scan Fourier transform infrared spectra composed a carbazole-based electron donor (CN-Cz2) and 1,3,5-triazine-based acceptor (PO-T2T) codeposited as solid film that gives intermolecular charge transfer (CT), TADF, record-high cyan organic light emitting diodes (external quantum efficiency: 16%). transient spectral assignment to CT state is unambiguous due its distinction from local excited either or chromophore. Importantly, broad absorption band centered at ~2060 cm −1 was observed assigned polaron-pair absorption. Time-resolved kinetics lead us conclude states relax ground-state intermediate with time constant ~3 µs, followed by relaxation original CN-Cz2:PO-T2T configuration within ~14 µs.