Boosting photoresponse and stability of a self-powered photoelectrochemical-type Bi₂Te₃ imaging photodetector by a novel quasi-solid-state gel electrolyte

Traditional photoelectrochemical-type (PEC-type) photodetectors have encountered several obstacles in practical application, such as the loss of photoelectrons due to interface charge recombination, short-term performance, and the problem of liquid electrolyte leakage. Herein, a novel quasi-solid-state polysulfide gel electrolyte (QSSPGE) is developed through the integration of liquid polysulfide into the polyvinyl alcohol (PVA) gel matrix. The PVA gel plays the dual function of passivating the surface trap states of bismuth telluride (Bi2Te3) nanosheets and suppressing the leakage and volatilization of the liquid polysulfide electrolyte. Impressively, the PEC-type Bi2Te3 photodetector based on the QSSPGE exhibits a boosted responsivity of 4.91 mA W-1 and a fast rise/ decay time of 14/99 ms under 365 nm illumination, outperforming the responsivity (4.32 mA W-1) of PEC-type Bi2Te3 photodetector based on liquid polysulfide. More importantly, the photocurrent density of the device remains at 95% and 81% of the initial value after being stored in air for one month and heated at 80 celcius for 240 min, respectively, demonstrating excellent long-term stability and thermal stability. Additionally, the high-resolution imaging capacity of the device is demonstrated. This work provides an effective strategy for fabricating highperformance, stable PEC-type optoelectronic devices.