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Abstract
This thesis reports the development of a near-infrared sensitive, solution-processible photoconductive device. It uses a composite of lead sulphide nanocrystals and a semiconducting polymer. The inclusion of nanocrystals into the polymer matrix is shown to make the material sensitive in the infrared from ∼800–1600 nm. Photocurrent internal quantum efficiencies of 3% under a 5 V bias are achieved. A photovoltaic response is demonstrated with an open circuit voltage of 0.36 V and an internal quantum efficiency of 0.006%; this efficiency is increased to 0.15% using a thermal treatment, and the maximum monochromatic power conversion efficiency achieved is 0.001%. Tunability of the photocurrent spectral response across the near-infrared region is achieved via control of the nanocrystal size during synthesis, with peaks centered at 955, 1200, and 1355 nm. Also investigated is the role in photoconduction of the organic ligands that passivate the nanocrystal surfaces.