Future applications of low dimensional structures in photovoltaics

This paper summarises our group's pioneering work on the photovoltaic applications of low dimensional structures and assesses the impact such structures could make in the future. We discuss the way quantum wells enahnce efficiency in lattice matched systems and our fundamental studies of radiative recombination that suggest that enhancements are possible in ideal cells. There is a problem when trying to enhance GaAs cells with quantum wells as there is no lattice matched lower band-gap ternary system. We present a novel strain-balanced GaAsP/InGaAs structure which can significantly enhance the efficiency of the leading GaInP/GaAs tandem cells. Quantum dots have been proposed for a number of photovoltaic applications. We discuss a novel application of single molecule precursor or colloidal quantum dots as the replacement for organic dyes in luminescent concentrators. The advantages include the ability to change the absorption threshold by choice of dot size and the possibility of reducing re-absorption by optimising the luminescent red-shift determined by the spread of dot sizes.