Synthesis and Optimization of Quantum Dot-Based Technologies: Solid-State Photovoltaics and Ferroelectric Particles
Wrenn, Toshia Lynn
:
2015-07-06
Abstract
Meaningful advances in quantum dot-based technologies will require revolutionary advances in synthetic strategies and materials characterization. The development of an all solid-state quantum dot-sensitized solar cell and the synthesis of ferroelectric particles via a simple, room-temperature treatment of quantum dots require a diverse integration of fabrication and characterization techniques.
Analysis of the photovoltaic response and material characterization of quantum dot-sensitized solar cells is used to determine the impact that deposition techniques have on the performance, material integration, and interfacial interactions within an interdigitated photovoltaic device containing a never-before utilized combination of TiO2 nanotubes, PbS quantum dots (QDs), and an conformal ITO film. The QDs are deposited using three different techniques: successive ion layer adsorption and reaction, electrophoretic deposition, and chemical-linking. Deposition of ITO was performed via electrochemically-assisted deposition or electron beam evaporation. Simulated solar illumination and current-voltage measurements show that devices containing chemically-linked PbS QDs and electron beam evaporated ITO generate the highest efficiency (10-3 W/m2) due to better QD-infiltration and more uniform coverage and infiltration of ITO.
Also, a novel synthetic protocol to generate ferroelectric particles, which are frequently utilized for an array of applications including non-volatile memory, renewable energy, and photodetection, by simply combining CdSe QDs with an equimolar solution of antimony trichloride is analyzed. The reaction pathway and projected source of the ferroelectric nature of the particles were assessed by examining untreated CdSe QDs and CdSe QDs treated with antimony trichloride for one minute and for 12 hours. Analysis indicates a two phase chemical reaction: initially Cl- disrupts and removes surface-passivating ligands, subsequently a cation-exchange between Cd and Sb produces anisotropic particles that demonstrate ferroelectric properties.