Light-enhanced reverse breakdown in Cu(In,Ga)Se2 solar cells

Szaniawski, Piotr; Lindahl, Johan; Törndahl, Tobias; Zimmermann, Uwe; Edoff, Marika

doi:10.1016/j.tsf.2012.09.022

Cited by 33 publications

(50 citation statements)

References 3 publications

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“…We selected Poole-Frenkel transport to model the reverse-breakdown effect because, unlike Zener and avalanche breakdown, it is consistent with the doping level of CIGS/CdS and with the observed temperature dependence of reverse breakdown in CIGS [6], [9]. Avalanche breakdown has an opposite temperature coefficient from the observed one, and given the typical doping of CdS and CIGS, avalanche breakdown voltage is expected to be approximately 10 V, which is much larger than the observed values.…”

Section: Compact Model Characteristicsmentioning

confidence: 99%

Thermal and Electrical Effects of Partial Shade in Monolithic Thin-Film Photovoltaic Modules

Silverman

Deceglie

Sun

et al. 2015

IEEE J. Photovoltaics

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Photovoltaic cells can be damaged by reverse bias stress, which arises during service when a monolithically integrated thin-film module is partially shaded. We introduce a model for describing a module's internal thermal and electrical state, which cannot normally be measured. Using this model and experimental measurements, we present several results with relevance for reliability testing and module engineering: Modules with a small breakdown voltage experience less stress than those with a large breakdown voltage, with some exceptions for modules having lightenhanced reverse breakdown. Masks leaving a small part of the masked cells illuminated can lead to very high temperature and current density compared with masks covering entire cells.

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Section: Compact Model Characteristicsmentioning

confidence: 99%

Thermal and Electrical Effects of Partial Shade in Monolithic Thin-Film Photovoltaic Modules

Silverman

Deceglie

Sun

et al. 2015

IEEE J. Photovoltaics

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“…CIGS and CdTe exhibit V BD s < 10 V and a decrease in V BD under illumination. This has been attributed to tunneling through defects at the buffer layer/CIGS interface . Partial shading has been shown to cause local current flow and the damage is exacerbated by the light dependence of the V BD , which causes even more of the current to selectively flow through the illuminated region.…”

Section: Introductionmentioning

confidence: 99%

Reverse Bias Behavior of Halide Perovskite Solar Cells

Bowring

Bertoluzzi

O’Regan

et al. 2017

Advanced Energy Materials

158

196

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solar cells have a breakdown voltage (V BD ) at which current starts to flow in reverse bias. When current flows in reverse bias, the shaded cell dissipates power rather than producing it, and this can cause local heating, which damages the cell. [8] Silicon cells generally breakdown in reverse bias by avalanche breakdown; the carriers gain enough kinetic energy from the applied electric field to generate additional carriers through impact ionization. V BD s for silicon cells are typically >15 V. If the pn junction is highly doped, the depletion width can narrow enough to allow tunneling in reverse bias. With either mechanism, breakdown current can get localized by uneven doping, crystalline defects, trace processing contaminants, etch sites, or edge effects causing damaging hot spots. CIGS and CdTe exhibit V BD s < 10 V and a decrease in V BD under illumination. This has been attributed to tunneling through defects at the buffer layer/CIGS interface. [9] Partial shading has been shown to cause local current flow and the damage is exacerbated by the light dependence of the V BD , which causes even more of the current to selectively flow through the illuminated region. This can cause localized shunting those results primarily in a permanent decrease in fill factor. [10] Stability in reverse bias has not been explored for perovskite solar cells, but there have been studies of MAPbI 3 memristors, [11][12][13][14] which require biasing in both forward and reverse directions, and photodetectors, which function in reverse bias. [15] Some memristors operate via the formation of metallic filaments through the perovskite [11,12] and others seem to function based on mobile defects in the perovskite. [12,13] Photodiodes of the structure fluorine-doped tin oxide (FTO)/porous TiO 2 /MAPbI 3 / Spiro-OMeTAD/Au show current multiplication in reverse bias, which has been attributed to mobile ion accumulation. [15] Mobile ions have also been used to explain hysteresis in current-voltage measurements. [16,17] In most cells, preconditioning at lower voltages makes cells worse, which is why scans from J SC to V OC tend to give lower efficiencies. It has also been demonstrated that mobile ions can cause band bending that can turn a symmetric device with nonselective contacts into a diode that functions as a solar cell. [18] Mobile ions likely also play an important role in the behavior of perovskite solar cells in reverse bias.In this paper, we first present a phenomenological study of reverse bias breakdown in halide perovskite solar cells. We characterize cells that have been held at constant current in the dark as they would be in a series connected module if only one cell were completely shaded. We also provide constant voltage measurements. We show how the reverse breakdownThe future commercialization of halide perovskite solar cells relies on improving their stability. There are several studies focused on understanding degradation under operating conditions in light, but little is known about the stability of these solar cells u...

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“…Given our purpose of studying shading effects, it is essential that the diode IV characteristics have the correct features under reverse bias. Experimentally, reverse breakdown voltages of V br ≈ −4 V in the dark and V br ≈ −2 V in light have been observed in pristine CIGS cells (Szaniawski et al, 2013;Puttnins et al, 2014). That light-enhanced reverse breakdown was found to be most pronounced for blue light rather than red.…”

Section: Electrical Currentmentioning

confidence: 89%

“…Spatial and temporal variations of current and temperature are calculated to better understand the stresses caused by shading and the concomitant reverse bias. The typically observed (Szaniawski et al, 2013;Puttnins et al, 2014) reverse break-down characteristic of CIGS devices is included in our model and we argue that the presence of low reverse breakdown voltage points (spatial nonuniformity) is a key factor in shading-induced failure. Our results demonstrate an example of thermal instability as a positive feedback mechanism in a nonuniform thinfilm, the physics of which was described in (Karpov, 2012).…”

Section: Introductionmentioning

confidence: 93%

Shading-induced failure in thin-film photovoltaic modules: Electrothermal simulation with nonuniformities

2016

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Finite element electrothermal modeling is employed to study shading-induced failure in monolithically integrated thin-film photovoltaic modules. A key element is spatial nonuniformity in current-voltage characteristics, which causes inhomogeneous current flow when part of a module is under reverse bias due to shading. Time-dependent calculations show that spots with lower reverse breakdown voltage experience greater current density and localized thermal runaway that can cause permanent damage, resulting in ohmic shunts. Such failure events lead to performance loss, especially when the module is in normal operating conditions and shunted currents lead to abnormally high module temperatures. Our simulations of temperature distributions, current-voltage characteristics, and electroluminescence are compared to data from the literature for copper indium gallium diselenide devices.

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Light-enhanced reverse breakdown in Cu(In,Ga)Se2 solar cells

Cited by 33 publications

References 3 publications

Thermal and Electrical Effects of Partial Shade in Monolithic Thin-Film Photovoltaic Modules

Thermal and Electrical Effects of Partial Shade in Monolithic Thin-Film Photovoltaic Modules

Reverse Bias Behavior of Halide Perovskite Solar Cells

Shading-induced failure in thin-film photovoltaic modules: Electrothermal simulation with nonuniformities

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