Ultra-stable and pH-universal photoelectrochemical photodetector achieved by CdSeTe/ZnS core-shell quantum dots

Emerging photoelectrochemical (PEC)-type photodetectors (PDs) have attracted increasing attention due to their low-cost manufacturing and liquid-phase working environment. However, the current reported PEC-PDs still suffer from relatively poor stability during operation in harsh and complex liquid environments, which hinders their practical applications. Here, a custom PD based on the CdSe 0.9 Te 0.1 /ZnS core-shell quantum dots (CSQDs) was constructed with optimized photocurrent density ( P ph ) of 7.36 μA∙cm −2 , photo-responsivity ( R ph ) of 701 μA∙W −1 and detectivity of 1.93  ×  10 8 Jones in basic electrolyte. Even in a highly corrosive acidic electrolyte, excellent photo-response performance was observed with P ph of 1.48 μA∙cm −2 and R ph of 6.88 μA∙W −1 . Strikingly, ultra-high photocurrent retention efficiency (PRE) values of 98.1 % and 74 % can be retained for measuring in 1.0 M KOH and HCl after sample stored for one month, respectively. Density functional theory calculations confirmed that the adsorption energy of CdSeTe/ZnS-OH/-H CSQDs are both weaker than CdSeTe-OH/-H QDs. This work presents a pH-universal photoactive material for PEC-PDs, and achieves one of the highest PRE values reported in PEC systems, demonstrating the enormous potential of CdSe 0.9 Te 0.1 /ZnS core/shell structure in enhancing device stability and overcoming the acid-hydrolysis problem of Cd-based materials.