Materials Based on Chitosan and Silver Iodide Nanoparticles as a Substrate for an Organic Thin-Film Photoresistor

In this work, thin-film photoresistors based on chitosan containing silver iodide (AgI) nanoparticles in various weight ratios (99.6 : 0.4; 99.2 : 0.8, and 98.4 : 1.6 wt %) have been studied. The spectral sensitivity of the composite film structures has been studied in the ranges of violet, green, and the full spectrum of solar radiation. It has been found that the samples with a ratio of 99.2 : 0.8 wt % demonstrate the maximum photoresistive response to violet light (ΔR/R up to 65% at an intensity of 10 mW/cm2), which is explained by an optimal percolation conduction mechanism. Weak sensitivity was observed for green light (ΔR/R < 15%), confirming the material’s selectivity to the short-wavelength range. The temporal characteristics demonstrate a response time of 1.2–1.8 s and a recovery time of 2.5–3.0 s.