The effect of barrier composition on quantum dot solar cell performance

The use of nanostructures such as quantum dots (QD) offers tremendous potential to realize high-efficiency photovoltaic (PV) cells. The optimization of the electronic structure of the layers within the QD region should lead to improved PV performance. This includes the QD layer itself, but also the surrounding barrier and/or strain balancing layers that comprise the QD active region. In this paper, the effect of the barrier layer composition (i.e. the cladding layers grown following QD capping layer) on the optoelectronic properties of InAs QDs was investigated. Specifically, the composition is changed from GaAs (1.42 eV) to InGaP (1.85 eV) and the effect of carrier collection and 1-sun efficiency is observed. The examination of the effects of these layers will contribute to understanding the dominant factor in carrier collection within QD-enhanced photovoltaics. In addition, the direct growth of InAs QD on InGaP surfaces is presented and compared to GaAs. The direct proximity of the InGaP surface greatly enlarges the InAs QD.