Quality control of polymer solar modules by lock-in thermography

Hoppe, Harald; Bachmann, J.; Muhsin, Burhan; Drüe, Karl-Heinz; Riedel, I.; Gobsch, G.; Buerhop‐Lutz, Claudia; Brabec, Christoph J.; Dyakonov, Vladimir

doi:10.1063/1.3272709

Cited by 52 publications

(32 citation statements)

References 8 publications

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“…Beyond the similar electrical characteristics of shunt currents, the statistical and spatial distribution of shunts also exhibits certain common features. In the literature there is considerable evidence from thermography 47,48 and luminescence 49 experiments demonstrating the localized nature of dark current conduction. Moreover, this localized conduction has also been correlated with the random shunt currents in the solar cell.…”

Section: B Physical Originmentioning

confidence: 99%

Universality of non-Ohmic shunt leakage in thin-film solar cells

Dongaonkar

Servaites

Ford

et al. 2010

Journal of Applied Physics

196

135

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This document has been made available through Purdue e-Pubs, a service of the Purdue University Libraries. Please contact epubs@purdue.edu for additional information. We compare the dark current-voltage ͑IV͒ characteristics of three different thin-film solar cell types: hydrogenated amorphous silicon ͑a-Si:H͒ p-i-n cells, organic bulk heterojunction ͑BHJ͒ cells, and Cu͑In, Ga͒Se 2 ͑CIGS͒ cells. All three device types exhibit a significant shunt leakage current at low forward bias ͑V Ͻ ϳ 0.4͒ and reverse bias, which cannot be explained by the classical solar cell diode model. This parasitic shunt current exhibits non-Ohmic behavior, as opposed to the traditional constant shunt resistance model for photovoltaics. We show here that this shunt leakage ͑I sh ͒, across all three solar cell types considered, is characterized by the following common phenomenological features: ͑a͒ voltage symmetry about V =0, ͑b͒ nonlinear ͑power law͒ voltage dependence, and ͑c͒ extremely weak temperature dependence. Based on this analysis, we provide a simple method of subtracting this shunt current component from the measured data and discuss its implications on dark IV parameter extraction. We propose a space charge limited ͑SCL͒ current model for capturing all these features of the shunt leakage in a consistent framework and discuss possible physical origin of the parasitic paths responsible for this shunt current mechanism.

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Section: B Physical Originmentioning

confidence: 99%

Universality of non-Ohmic shunt leakage in thin-film solar cells

Dongaonkar

Servaites

Ford

et al. 2010

Journal of Applied Physics

196

135

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“…Furthermore, the dissipative loss patterns are the origin of respective heat patterns, which are visible in dark lock-in thermography imaging experiments. Thermographic imaging is excellently suitable to represent the aforementioned losses under operating conditions [1][2][3]. Remarkable agreement was found between the experimental and calculated thermography results in defect-free solar cells.…”

Section: Extended Abstractmentioning

confidence: 55%

Current Density and Resistive Loss Patterns in Defect-free and Defective Organic Solar Cells by Finite Element Modelling

Öttking¹,

Rösch²,

Fluhr³

et al. 2016

Proceedings of the 2016 International Conference on Quantitative InfraRed Thermography

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Finite element models of different laterally extended polymer solar cells were applied in order to investigate current pathways and dissipative losses in organic solar cells, especially in the presence of local shunt defects. The models are of purely resistive nature, as this is sufficient to describe the effects under consideration. Remarkable agreement was found between the experimental and calculated thermography results in defect-free solar cells. All this provides a further step towards a quantitative description of the losses in defect-free and defective solar cells. Extended AbstractWe constructed finite element models of different laterally extended polymer solar cells in order to investigate current pathways and dissipative losses in organic solar cells, especially in the presence of local shunt defects. The models are of purely resistive nature, as this is sufficient to describe the effects under consideration.The model calculations yield the spatial distribution of the current densities, potentials and the according resistive losses. In defect-free solar cells, the current density and loss patterns cover the entire area of the transparent electrode (ITO). In the close vicinity of the shunt defects, the current density exhibits large maxima leading to respective maxima in the power loss. On the other hand, non-negligible currents are spread out covering the entire area of the devices, running along the electric potential gradient.The current density mainly contributes to the resistive loss density of the device. The loss, in turn, is a consequence of the delicate interplay between the individual layer properties, namely the resistivities and layer thicknesses in combination, also in the presence of locally concentrated defects. Furthermore, the dissipative loss patterns are the origin of respective heat patterns, which are visible in dark lock-in thermography imaging experiments. Thermographic imaging is excellently suitable to represent the aforementioned losses under operating conditions [1][2][3]. Remarkable agreement was found between the experimental and calculated thermography results in defect-free solar cells. (cf. Figs. 1,2) All this provides a further step towards a quantitative description of the losses in defect-free and defective solar cells.

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“…LIT have been used to image modules [106,107] while a combination of DLIT, PL, EL and reflectance imaging have successfully been used to identify defects in R2R printed modules [108]. However, of these methods only the optical reflectance inspection is suitable for high speed in-line characterization due to the long measurement times needed for the other methods.…”

Section: Imaging Of Modulesmentioning

confidence: 99%

Optoelectrical Imaging Methods for Organic Photovoltaic Materials and Moduls

Bergqvist¹

2015

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Linköping 2015 IICover image: LED array based photocurrent imaging method for in-line characterization of printed organic solar cells developed during the course of this thesis. Illustration by Cecilia Kornehed.During the course of research underlying this thesis, Jonas Bergqvist was enrolled in Agora Materiae, a multidisciplinary doctoral program at Linköping University, Sweden. III AbstractTo achieve a high living standard for all people on Earth access to low cost energy is essential. The massive burning of fossil fuels must be drastically reduced if we are to avoid large changes of our climate. Solar cells are both technologically mature and have the potential to meet the huge demand for renewable energy in many countries. The prices for silicon solar cells have decreased rapidly during the course of this thesis and are now in grid parity in many countries.However, the potential for even lower energy costs has driven the research on polymer solar cells, a class of thin film solar cells. Polymer solar cells can be produced by roll to roll printing which potentially enables truly low cost solar cells. However, much research and development remain to reach that target.Polymer solar cells consist of a semiconducting composite material sandwiched between two electrodes, of which one is transparent, to let the light energy in to the semiconductor where it is converted to electric energy. The semiconductor comprise an intimate blend of polymer and fullerenes, where the nanostructure of this blend is crucial for the photo current extraction.To reach higher solar cell performance the dominating strategy is development and fine tuning of new polymers. To estimate their potential as solar cell materials their optical response have been determined by spectroscopic ellipsometry. Furthermore, optical simulations have been performed where the direction dependency of the optical response of the transparent electrode material PEDOT:PSS have been accounted for. The simulations show reduced electrode losses for light incident at large oblique angles.Moreover, we have shown that a gentle annealing of the active layer induces a local conformational changes of an amorphous polymer that is beneficial for solar cell performance. The active layer is deposited from solution where the drying kinetics determine the final nanostructure. We have shown that using in-situ photoluminescence phase separation can be detected during the drying process while a reflectance method have been developed to image lateral variations of solvent evaporation rate.Imaging methods are important tools to detect performance variations over the solar cell area. For this purpose an intermodulation based photo current imaging method have been developed to qualitatively differentiate the major photo current loss mechanisms. In addition, a 1D LED-array photo current imaging method have been developed and verified for high speed in-line characterization of printed organic solar modules. IV Populärvetenskaplig sammanfattningFör att uppnå en hög levnadsstandard för...

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Quality control of polymer solar modules by lock-in thermography

Cited by 52 publications

References 8 publications

Universality of non-Ohmic shunt leakage in thin-film solar cells

Universality of non-Ohmic shunt leakage in thin-film solar cells

Current Density and Resistive Loss Patterns in Defect-free and Defective Organic Solar Cells by Finite Element Modelling

Optoelectrical Imaging Methods for Organic Photovoltaic Materials and Moduls

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