Thieno[1, 3, 2]oxazaborinine-containing aza-BODIPYs with near infrared absorption bands: synthesis, photophysical properties, and device applications. (8th November 2019)

• Record Type: Journal Article
• Authors: Kubo, Yuji; Shimada, Takuma; Maeda, Kentaro; Hashimoto, Yuta
• Is Part Of: New journal of chemistry. Volume 44:Number 1(2020)
• Page Start: 29
• Page End: 37
• Publication Date: 2019-11-08
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/c9nj04612g
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : Structurally constrained NIR aza-BODIPYs with thieno[1, 3, 2]oxazaborinine were synthesized for the first time, enabling their evaluation as NIR photodetectors through fabrication of a single-component device. Abstract : As part of an ongoing study of near infrared (NIR) absorbing dyes applicable to optoelectronics, thieno[1, 3, 2]oxazaborinine-containing aza-BODIPYs were synthesized for the first time. 3, 5-Di(thiophene)-substituted N2 O2 -type 1 showed a NIR absorption band centered at 780 nm, with a molar extinction coefficient ( ε max ) of 5.51 × 10 4 M −1 cm −1 in CH2 Cl2 ; however, it was easily hydrolyzed in solution. In comparison, 3-thiophene-containing N2 O-type analogues 2 and 3 had greater stability, and NIR absorption bands at 768 nm ( ε max = 8.62 × 10 4 M −1 cm −1 ) and 779 nm ( ε max = 6.32 × 10 4 M −1 cm −1 ), respectively, in CH2 Cl2 . Notably, these dyes had longer absorption bands than those of all of the structurally constraining aza-BODIPYs reported thus far. CV measurements and theoretical calculations indicated that this shift was the result of a higher-lying HOMO energy level generated by incorporation of thiophene into the aza-BODIPY core. As a potential device application, the 3 -loaded film was prepared on indium tin oxide (ITO). The film showed a NIR absorption band at 827 nm, with a wide spectral range, and a λ onset value of 897 nm; thus, its applicability as a NIR photodetector was evaluated through fabrication of a single-component device. The ITO/3 (85 nm)/Al (100 nm) device produced a photocurrent of 9.57 × 10 −7 A cm −2 at a bias potential of 1 V upon illumination at 850 nm and a fluence of 130 μW cm −2 . This demonstrated the potential of thieno[1, 3, 2]oxazaborinine-containing aza-BODIPY materials in optoelectronic applications such as NIR photodetectors.