|
|||||
|
|
An Electron-Accepting aza-BODIPY-Based Donor–Acceptor–Donor Architecture for Bright NIR Emission |
|
| Authors: | Dr Yuto Kage Seongsoo Kang Dr Shigeki Mori Dr Masashi Mamada Prof?Dr Chihaya Adachi Prof?Dr Dongho Kim Prof?Dr Hiroyuki Furuta Prof?Dr Soji Shimizu |
| Institution: | 1. Department of Chemistry and Biochemistry, Graduate School of, Engineering, Kyushu University, Fukuoka, 819-0395 Japan;2. Spectroscopy Laboratory for Functional π-Electronic Systems, Department of Chemistry, Yonsei University, Seoul 03722, Korea;3. Advanced Research Support Center (ADRES), Ehime University, Matsuyama, 790-8577 Japan |
| Abstract: | A bright near-infrared (NIR) fluorescent molecule was developed based on the donor–acceptor–donor (D–A–D) approach using an aza-BODIPY analog called pyrrolopyrrole aza-BODIPY (PPAB) as an electron-accepting chromophore. Directly introducing electron-donating triphenylamine (TPA) to develop a D–A–D structure caused redshifts of absorption and emission of PPAB into the NIR region with an enhanced fluorescence brightness of up to 5.2×104 m ?1 cm?1, whereas inserting a phenylene linker between the TPA donor and the PPAB acceptor induced solvatochromic behavior in emission. Transient absorption spectra and theoretical calculations revealed the presence of a highly emissive hybridized locally excited and charge-transfer state in the former case and the contribution of the dark charge-separated state to the excited state in the latter case. The bright D–A–D PPAB as a novel emitter resulted in a NIR electroluminescence with a high external quantum efficiency of 3.7 % and a low amplified spontaneous emission threshold of ca. 80 μJ cm?2, indicating the high potential for NIR optoelectronic applications. |
| Keywords: | aza-BODIPY fluorescence near infrared organic light emitting diode transient absorption spectroscopy |