An Electron-Accepting aza-BODIPY-Based Donor-Acceptor-Donor Architecture for Bright NIR Emission

Yuto Kage; Seongsoo Kang; Shigeki Mori; Masashi Mamada; Chihaya Adachi; Dongho Kim; Hiroyuki Furuta; Soji Shimizu

doi:10.1002/chem.202005360

An Electron-Accepting aza-BODIPY-Based Donor-Acceptor-Donor Architecture for Bright NIR Emission

Chemistry. 2021 Mar 17;27(16):5259-5267. doi: 10.1002/chem.202005360. Epub 2021 Feb 19.

Authors

Yuto Kage¹, Seongsoo Kang², Shigeki Mori³, Masashi Mamada^{1

4}, Chihaya Adachi^{1

4

5}, Dongho Kim², Hiroyuki Furuta^{1

6}, Soji Shimizu^{1

6}

Affiliations

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.
⁴ Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, Fukuoka, 819-0395, Japan.
⁵ International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka, 819-0395, Japan.
⁶ Center for Molecular Systems (CMS), Kyushu University, Fukuoka, 819-0395, Japan.

PMID: 33442895
DOI: 10.1002/chem.202005360

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.

Abstract

Grants and funding