Rational Molecular Design towards Vis/NIR Absorption and Fluorescence by using Pyrrolopyrrole aza‐BODIPY and its Highly Conjugated Structures for Organic Photovoltaics |
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| Authors: | Prof?Dr Soji Shimizu Taku Iino Prof?Dr Akinori Saeki Prof?Dr Shu Seki Prof?Dr Nagao Kobayashi |
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| Affiliation: | 1. Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Fukuoka 819‐0395 (Japan);2. Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980‐8578 (Japan);3. Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, 565‐0871 (Japan) |
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| Abstract: | Pyrrolopyrrole aza‐BODIPY (PPAB) developed in our recent study from diketopyrrolopyrrole by titanium tetrachloride‐mediated Schiff‐base formation reaction with heteroaromatic amines is a highly potential chromophore due to its intense absorption and fluorescence in the visible region and high fluorescence quantum yield, which is greater than 0.8. To control the absorption and fluorescence of PPAB, particularly in the near‐infrared (NIR) region, further molecular design was performed using DFT calculations. This results in the postulation that the HOMO–LUMO gap of PPAB is perturbed by the heteroaromatic moieties and the aryl‐substituents. Based on this molecular design, a series of new PPAB molecules was synthesized, in which the largest redshifts of the absorption and fluorescence maxima up to 803 and 850 nm, respectively, were achieved for a PPAB consisting of benzothiazole rings and terthienyl substituents. In contrast to the sharp absorption of PPAB, a PPAB dimer, which was prepared by a cross‐coupling reaction of PPAB monomers, exhibited panchromatic absorption across the UV/Vis/NIR regions. With this series of PPAB chromophores in hand, a potential application of PPAB as an optoelectronic material was investigated. After identifying a suitable PPAB molecule for application in organic photovoltaic cells based on evaluation using time‐resolved microwave conductivity measurements, a maximized power conversion efficiency of 1.27 % was achieved. |
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| Keywords: | chromophores density functional calculations fluorescence spectroscopy fluorescent probes UV/Vis spectroscopy |
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