Quantum Interference Measurements and Their Application to Analysis of Ultrafast Photocarrier Dynamics in Semiconductor Solar Cell Materials

Abstract

Quantum interference measurement is a powerful method to analyze electronic dynamics using phase information of optical fields and electronic states during various types of optical excitation processes. This method is particularly useful for accurate measurements of photocarrier generation processes in semiconductor solar cell materials. Two quantum interference methods, namely photocurrent beat spectroscopy and phase-locked pulses transient absorption spectroscopy, are recently developed to analyze ultrafast photocarrier generation processes. This review describes how these two techniques can be employed to identify electronic states contributing to photon-to-current conversion processes in solar cell materials. Two types of states are highlighted: (i) localized levels within the bandgaps of bulk crystals and thin films leading to photocarrier generation, and (ii) exciton complexes in nanocrystals whose ultrafast dynamics directly influence the efficiency of photoabsorption processes. Since quantum interference measurements provide quantum phase information that is not accessible by other conventional methods, they can also be utilized for advanced evaluation and optimization of optoelectronic materials and devices.