Carbon dot / thermo-responsive polymer capacitive wavelength-specific photodetector

Organic photodetectors are considered attractive alternatives to inorganic, semiconductor-based devices. We constructed a wavelength-specific capacitive photodetector, comprising carbon dots (C-dots) and poly-(N-isopropylacrylamide) (PNIPAM), a thermo-responsive polymer. Upon illuminating the C-dot/PNIPAM composite, light absorbed by the C-dots is released as heat; the photothermal effect gives rise to a rapid temperature increase con-sequently affecting structural transformation of the PNIPAM host and concomitant change in the recorded capacitance. Importantly, wavelength sensitivity of the photodetector is determined by the excitation wavelength of the embedded C-dots; we show that tuning the wavelength response of the system can be readily achieved through selection of the C-dot species incorporated within the PNIPAM matrix. The C-dot/PNIPAM photodetector ex-hibits reversibility and rapid light response, is synthesized from inexpensive and recyclable building blocks. The technology may be employed for photo-switching, photoinduced ca-pacitors, smart windows, and other photo-electronic applications.