Review of the mechanisms for the phonon bottleneck effect in III-V semiconductors and their application for efficient hot carrier solar cells

The hot carrier solar cell aims to significantly boost the power conversion efficiency through fully utilizing the carrier thermalization energy loss. To realize such ultraefficient solar cells, it requires that the excess energy of excited hot carriers is captured for power generation by reducing the rate of, or even preventing, carrier cooling. It has been known that phonon bottleneck effects (PBE) play the most decisive role in reducing the carrier thermalization rate. However, the mechanisms underlying PBE are complex and vary in different material systems and are influenced by many factors such as illumination intensity and carrier density (extrinsic), electronic band structure, and phonon dispersion (intrinsic) and quantum confinement (intrinsic). III-V semiconductors are the most popular photovoltaic materials for ultraefficient thin film solar cells due to their high crystal quality and adjustable electronic band structure. Such features reduce some of the complexity of the study of PBE and hot carrier dynamics. Therefore, it is appropriate to identify the PBE mechanisms in these III-V semiconductors. This manuscript systematically reviews the mechanisms underlying PBE in III-V semiconductors in both bulk and nanostructures. There is a tendency for an enhanced PBE in low-dimensional III-V semiconductors due to quantum and other confinement effects. Multiple quantum wells seem the most promising material system for hot carrier solar cells.

Automated summary

The hot carrier solar cell aims to increase energy conversion efficiency by capturing the excess energy of excited hot carriers. Phonon bottleneck effects (PBE) play a decisive role in reducing carrier thermalization rate. This study systematically reviews the mechanisms of PBE in III-V semiconductors, highlighting the enhanced PBE in low-dimensional III-V semiconductors due to quantum confinement effects.