Comment on "Optical Imaging of Light-Induced Thermopower in Semiconductor" [Phys. Rev. Applied 5, 024005 (2016)]

TL;DR

This paper critiques a recent method for measuring thermopower via photoluminescence, highlighting a fundamental conceptual error in the original definition of the Seebeck coefficient.

Contribution

It clarifies the correct physical quantities needed to accurately determine thermopower and points out the errors in the previous methodology.

Findings

Identifies a confusion between physical quantities in the original method.

Provides a corrected understanding of thermopower measurement.

Highlights the importance of proper definitions in thermoelectric measurements.

Abstract

In a recent article [Phys. Rev. Applied 5, 024005 (2016)], Gibelli and coworkers proposed a method to determine the thermopower, i.e. the Seebeck coefficient, using photoluminescence measurements. The photoluminescence spectra are used to obtain the local gradients of both the electrochemical potential difference between electron and holes and the temperature of the electron-hole plasma. However, the definition of the thermopower given in that article seems erroneous due to a confusion between the different physical quantities needed to derive this parameter.