Low bandgap donor-acceptor-donor-based TPA-azaBODIPY-TPA small molecule for flexible near-infrared organic photodetectors

Abstract

Organic photodetectors (OPDs) hold great promise for use in flexible electronics as they can be designed on substrates featuring various shapes and using cost-effective solution-processed methods. Organic conjugated materials offering two or more distinct optoelectronic functions are especially appealing here as they provide multifunctionality while also retaining the ease of fabrication and low-cost advantage. One such material is TPA-azaBODIPY-TPA that has been shown to feature ideal charge transfer properties and excitation energy levels. In our recent work, we demonstrated the versatile nature of this material acting as either a charge transport interlayer in perovskite solar cells, or as a light-absorbing layer in OPDs. TPA-azaBODIPY-TPA-based solar cells showed a 60 % increase in power conversion efficiency when compared to a control device using a conventional interlayer PEDOT:PSS. Having also demonstrated the successful utilization of TPA-azaBODIPY-TPA in OPDs manufactured on glass substrates, we further explore its applications in the design and fabrication of flexible OPDs for near-infrared sensing. Fabricated devices on flexible substrates show a near-infrared spectral responsivity of 49 mA W -1 at 730 nm, a high linear dynamic range of 110 dB and fast temporal responses below 100 μs. With robust thermal stability as well as excellent solubility and processability, TPA-azaBODIPY-TPA is found to be perfect candidate for the next-generation of smart optoelectronic flexible devices.