Solution-processed Optoelectronic Devices from Colloidal Quantum Dots

This book contains design, synthesis, fabrication and testing of optoelectronic devices which are composed of colloidal inorganic semiconductor materials and fabricated by potentially low-cost solution-processing methods. The first part of this book demonstrates a novel fabrication method where colloidal quantum dots (QDs) are self-assembled layer-by-layer into a thin film structure through electrostatic interaction. This process allows precise control of QD thin film thickness by self-assembly and can in principle be applied to a wide range of substrates. Using such QD thin films, photoconductor photodetectors and metal-intrinsic-metal photodiodes have been demonstrated. In the second part of this dissertation, heavy-metal-free colloidal Si materials are synthesized by electrochemical etching Si wafers, followed by surface modification and ultra-sonication for dispersion of Si nano- and/or micro-particles in various solvents. Demonstrated applications include RGB photoluminescent Si phosphors, scattering-enhanced Si nano-/micro-particle composite photodetectors and hybrid Si QD-organic light-emitting-diodes (LEDs).