Solution processed organic-inorganic hybrid nanocomposites: Photoconduction and photorefraction
Roy Choudhury, Kaushik
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Conjugated polymer-based electronics and photonics are rapidly emerging as a low-cost, multifunctional alternative to traditional semiconductor based optoelectronics. With the advent of soft inorganic chemistry processes leading to the rapid development of nanocrystal technology, a new means of photosensitizing polymeric composites has been realized enabling monolithic integration of active photonic components into devices. As a result, hybrid organic-inorganic materials have emerged as a novel class of optoelectronic media for a number of potential technological applications. This thesis presents investigations concerning the successful implementation of inorganic semiconductor nanocrystals to photosensitize polymer-based photoconductive and photorefractive materials. Colloidally synthesized nanocrystals, active over a wide spectral range were incorporated into polymeric composites leading to efficient photoconduction and photorefraction. Use of narrow-band gap semiconductor nanocrystals of appropriate size allowed for the extension of photosensitivity of the devices into the technologically important infrared communication wavelengths. Finally, the ability to combine the broad spectral access enabled by nanocrystal photosensitization with other means of enhancing the photoresponse of the devices is explored. Here, a high-mobility organic semiconducting molecule is employed to boost the conductivity of the nanocomposite in one instance, while nanocrystals conjugated to single-walled carbon nanotubes are used to demonstrate enhanced harvesting of incident light in the other. Devices realized from both of these novel composites exhibited superior performance.