The Implementation of Quantum Dots in Photovoltaics: From Semiconductor-Plasmon Interactions to Current Visualization

Abstract

This thesis presents two avenues through which solution processable and electronically tunable QDs are investigated as active absorbers in photovoltaic applications. First, the synthesis and characterization of CuxInyS2 QDs with localized surface plasmon resonance (LSPR) modes is presented. The potential benefits of near-field plasmonic effects centered upon light absorbing nanoparticles in a photovoltaic system is investigated by developing and verifying nonplasmonic CuInS2 QD “twins” as an experimental control. Simple QD-sensitized solar cells (QD-SSCs) were assembled which showed an 11.5% relative increase of efficiency in the plasmon-enhanced devices, attributed to augmented charge excitation due to near-field “antenna” effects in the plasmonic QDs. Second, electron beam-induced current (EBIC) is correlated with high-resolution device cross section elemental maps and bulk PV properties of thin film depleted-heterojunction PVs utilizing PbS QDs. EBIC is shown to effectively gauge the spatial extent of the depletion region within the QD active layer. Furthermore, elemental maps show penetration of QDs deep into the mesoporous TiO2 layer, an unexpected finding that has significant implications in the electrical modeling of these devices.