Microscopic observation of carrier-transport dynamics in quantum-structure solar cells using a time-of-flight technique

TL;DR

This paper introduces a time-of-flight technique to directly observe and measure carrier transport dynamics in quantum-structure solar cells, providing detailed insights into microscopic carrier behavior at room temperature.

Contribution

The study presents a novel, real-time method for evaluating carrier transport in quantum structures, enhancing understanding of carrier dynamics in solar cell active regions.

Findings

Carrier transport time can be efficiently measured at room temperature.

The drift velocity depends linearly on the internal electric field.

The quantum structure behaves as a quasi-bulk material with low effective mobility.

Abstract

In this study, we propose a carrier time-of-flight technique to evaluate the carrier transport time across a quantum structure in an active region of solar cells. By observing the time-resolved photoluminescence signal with a quantum-well probe inserted under the quantum structure at forward bias, the carrier transport time can be efficiently determined at room temperature. The averaged drift velocity shows linear dependence on the internal field, allowing us to estimate the quantum structure as a quasi-bulk material with low effective mobility containing the information of carrier dynamics. We show that this direct and real-time observation is more sensitive to carrier transport than other conventional techniques, providing better insights into microscopic carrier transport dynamics to overcome a device design difficulty.