Investigation of capacitance transients in CuInS2 due to ionic migration

Loef, Ruben; Schoonman, J.; Goossens, Albert

doi:10.1016/j.solmat.2008.07.005

Cited by 9 publications

(7 citation statements)

References 45 publications

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“…This seemed plausible given the previous reports of TID behavior in both polycrystalline CdTe [4] and CuInSe 2 [5] devices which themselves were based upon earlier works by Heiser and Mesli [6] and subsequently, Lyubomirsky, et al [7]. In the TID model for hysteresis, the higher W d measured during the rev-voltage scan is due to the screening of the space-charge region, not by holes, but rather by positively charged Cu-interstitial donors, Cu i + .…”

Section: Introductionsupporting

confidence: 58%

Effect of hysteresis on measurements of thin-film cell performance

Albin

Cueto

2010

SPIE Proceedings

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Printed on paper containing at least 50% wastepaper, including 10% post consumer waste. Effect of Hysteresis on Measurements of Thin-Film Cell PerformanceDavid Albin* and Joseph del Cueto National Renewable Energy Laboratory, 1617 Cole Blvd., Denver, CO, USA 80401 ABSTRACT 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 (V oc ), up to 10 mV, and smaller short-circuit current density (J sc ), by up to 2 mA/cm 2 , relative to scanning voltage in a forward-to-reverse direction. The variation at the maximum power point, P max , is however small. The resulting variation in FF can be as large as 3%. When Cu is not added, hysteresis in both V oc and J sc is negligible however P max hysteresis is considerably greater. This behavior corroborates observed changes in depletion width, W d , derived from capacitance (C) vs voltage (V) scans. Measured values of W d 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 ºC correlates with increased space-charge recombination. Voltagedependent collection however was not observed to increase with stress in these cells.

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Section: Introductionsupporting

confidence: 58%

Effect of hysteresis on measurements of thin-film cell performance

Albin

Cueto

2010

SPIE Proceedings

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“…Additional theories on the microscopic processes leading to metastable changes in CIGS performance include ionic drift models, which suggest that the motion of ionic species including indium and copper may be responsible for light-dark performance differences of CIGS devices 11 . It is possible that multiple mechanisms are responsible for device performance changes on different time scales, with longer-term performance change driven by ionic motion rather than reversible population and depopulation of electronic states.…”

Section: Introductionmentioning

confidence: 99%

Electrical bias as an alternate method for reproducible measurement of copper indium gallium diselenide (CIGS) photovoltaic modules

et al. 2012

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Light-to-dark metastable changes in thin-film photovoltaic (PV) modules can introduce uncertainty when measuring module performance on indoor flash testing equipment. This study describes a method to stabilize module performance through forward-bias current injection rather than light exposure. Measurements of five pairs of thin-film copper indium gallium diselenide (CIGS) PV modules indicate that forward-bias exposure maintained the PV modules at a stable condition (within 1%) while the unbiased modules degraded in performance by up to 12%. It was also found that modules exposed to forward bias exhibited stable performance within about 3% of their long-term outdoor exposed performance. This carrier-injection method provides a way to reduce uncertainty arising from fast transients in thin-film module performance between the time a module is removed from light exposure and when it is measured indoors, effectively simulating continuous light exposure by injecting minority carriers that behave much as photocarriers do. This investigation also provides insight into the initial light-induced transients of thin-film modules upon outdoor deployment.

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“…Some of these longer-term exposure changes can be reversed when the modules are put into dark storage, defined as low-light-level conditions at room temperature, in periods of days to weeks. 14 Copper inclusion in the back-side contact of CdTe modules can improve the ohmic connection with the high-work-function p-CdTe layer. In CIGS modules, metastable changes have been attributed to persistent photoconductivity in the bulk CIGS 11 and to charging-discharging of defect states at the CdS/CIGS interface.…”

Section: Introductionmentioning

confidence: 99%

Metastable electrical characteristics of polycrystalline thin-film photovoltaic modules upon exposure and stabilization

et al. 2012

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The significant features of a series of stabilization experiments conducted at the National Renewable Energy Laboratory (NREL) between May 2009 and the present are reported. These experiments evaluated a procedure to stabilize the measured performance of thin-film polycrystalline cadmium telluride (CdTe) and copper indium gallium diselenide (CIGS) thin-film photovoltaic (PV) modules. The current-voltage (I-V) characteristics of CdTe and CIGS thinfilm PV devices and modules exhibit transitory changes in electrical performance after thermal exposure in the dark and/or bias and light exposures. We present the results of our case studies of module performance versus exposure: light soaked at 65°C; exposed in the dark under forward bias at 65°C; and, finally, longer-term outdoor exposure. We find that stabilization can be achieved to varying degrees using either light-soaking or dark-bias methods and that the existing IEC 61646 light-soaking interval may be appropriate for CdTe and CIGS modules with one caveat: it is likely that at least three exposure intervals are required for stabilization.

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Investigation of capacitance transients in CuInS2 due to ionic migration

Cited by 9 publications

References 45 publications

Effect of hysteresis on measurements of thin-film cell performance

Effect of hysteresis on measurements of thin-film cell performance

Electrical bias as an alternate method for reproducible measurement of copper indium gallium diselenide (CIGS) photovoltaic modules

Metastable electrical characteristics of polycrystalline thin-film photovoltaic modules upon exposure and stabilization

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