Generalized analysis of quasi-steady-state and transient decay open circuit voltage measurements

TLDR

Open‑circuit voltage measured as a function of slowly varying light intensity determines the current–voltage characteristics of solar cells and photodiodes. This article presents a detailed theoretical analysis of quasi‑steady‑state Voc measurements and demonstrates that the technique can accurately determine minority carrier lifetime using a new generalized analysis. The QssVoc technique, combined with a new generalized analysis, enables accurate determination of minority carrier lifetime. Experimentally, the analysis retrieves true steady‑state characteristics for high‑lifetime, high‑resistivity silicon devices and shows that device characteristics can be obtained from either photoconductance or open‑circuit voltage measurements, even with transient techniques.

Abstract

The current–voltage characteristics of solar cells and photodiodes can be determined by measuring the open-circuit voltage as a function of a slowly varying light intensity. This article presents a detailed theoretical analysis and interpretation of such quasi-steady-state Voc measurements (QssVoc). The ability of this analysis to accurately obtain the true steady-state device characteristics even in the case of high lifetime, high resistivity silicon devices is demonstrated experimentally. The QssVoc technique can be used to determine the minority carrier lifetime, and the new generalized analysis is required to do this accurately. An important outcome is that solar cell and diode device characteristics can be obtained from measurements of either the photoconductance or the open-circuit voltage, even using transient techniques.