METASTABILITY IN FLEXIBLE CIGS SOLAR CELLS INVESTIGATED BY ACCURATE MEASUREMENT OF OPEN-CIRCUIT VOLTAGE TRANSIENTS

摘要

When measuring the transient behavior of Voc under illumination in solar cells based on Cu(In, Ga)Se_2, it is essential to carefully record and correct for the inevitable temperature drift in order to reliably characterize the metastability of the material. It turns out, that Voc is a linear function of the logarithm of time and its slope can be taken as a measure for the degree of metastability. Together with those of measurements of the relaxation process, which is observed as transient capacitance in the dark, the results support the assumption that the metastability is related to changes in acceptor concentration. However, details of macroscopic manifestation of the microscopic mechanism remain to be explained within the framework of an appropriate model.