The enhanced lifetime of printed GaS-based photodetectors with polymer encapsulation

Exhibiting excellent absorption in the UV–visible wavelength range makes layered gallium sulfide (GaS) semiconductor material a promising candidate for use in electronics and optoelectronics applications. Recently, a fully printed GaS-based photodetector has been proposed and fabricated, rendering a low-cost fabrication process in flexible electronics. However, the degradation of the semiconductor layer due to environmental conditions causes reliability issues and shortens their lifetime. Thus, in this study, an attempt has been made to encapsulate printed GaS-based photodetector using different polymers to hinder the degradation. It is demonstrated that encapsulating the printed GaS-based photodetector by utilizing the polymer-capping method with styrene co-polymers, Polystyrene-block-polyisoprene-block-polystyrene, highly hydrogenated poly(styrene)-block-poly(butadiene), partially hydrogenated poly(styrene)-block-poly(butadiene), increases the performance of the photodetector. The efficiency of the GaS-based photodetector printed on flexible polyethylene terephthalate (PET) substrate has reached up to 123 % in responsivity in 6 weeks after the polymer coating. Also, the device figure of merit, the detectivity value of the printed photodetector, has increased more than three times after the polymer coating compared to its as-deposited state. Meanwhile, it is observed that the fall and rise times of the printed GaS photodetector have remained constant. Based on these results attained in this study, it can be claimed that the polymer coating provides high performance and long stability in the printed GaS-based photodetectors on flexible substrates, which will pave the way for the further implementations of III-VI group layered semiconductor materials in electronics and optoelectronics applications.