Effect of hysteresis on measurements of thin-film cell performance
By: David Albin and Joseph del Cueto
Contributors: Cueto, J. A. del; Society of Photo-optical Instrumentation Engineers; National Renewable Energy Laboratory (U.S.)
Series: NREL/CP -- 5200-48996; Conference paper (National Renewable Energy Laboratory (U.S.)) -- NREL/CP-5200-48996.
Publisher: National Renewable Energy Laboratory
Published: 2011
Place of publication: Golden, CO]
Language: eng
Format: [electronic resource] /
Subjects: Photovoltaic cells; Research; Solar cells; Design and construction; Thin films; Hysteresis; Copper
Description: Transient or hysteresis effects in polycrystalline thin film CdS/CdTe cells are a function of pre-measurement voltage bias and whether Cu is introduced as an intentional dopant during back contact fabrication. When Cu is added, the current-density (J) vs. voltage (V) measurements performed in a reverse-to-forward voltage direction will yield higher open-circuit voltage (Voc), up to 10 mV, and smaller short-circuit current density (Jsc), by up to 2 mA/cm2, relative to scanning voltage in a forward-to-reverse direction. The variation at the maximum power point, Pmax, is however small. The resulting variation in FF can be as large as 3%. When Cu is not added, hysteresis in both Voc and Jsc is negligible however Pmax hysteresis is considerably greater. This behavior corroborates observed changes in depletion width, Wd, derived from capacitance (C) vs voltage (V) scans. Measured values of Wd are always smaller in reverse-to-forward voltage scans, and conversely, larger in the forward-to-reverse voltage direction. Transient ion drift (TID) measurements performed on Cu-containing cells do not show ionic behavior suggesting that capacitance transients are more likely due to electronic capture-emission processes. J-V curve simulation using Pspice shows that increased transient capacitance during light-soak stress at 100 degrees C correlates with increased space-charge recombination. Voltage-dependent collection however was not observed to increase with stress in these cells.
Notes: Title from title screen (viewed March 21, 2011).

"March 2011."

"Presented at the Reliability of Photovoltaic Cells, Modules, Components, and Systems III: SPIE Conference, San Diego, California, August 3-5, 2010."

Includes bibliographical references (p. 9).

DE-AC36-08GO28308 PVA9.2450

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