Assignment of capacitance spectroscopy signals of CIGS solar cells to effects of non-ohmic contacts

We report evidence for the identification of the capacitance transients detected at room temperature for thin-film photovoltaic cells with CIGS absorbers as an additional non-ohmic contact in the structure with a time constant larger than that of the solar cell p–n junction. The N1 signal was recent...

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Vydáno v:Solar energy materials and solar cells Ročník 112; s. 78 - 83
Hlavní autoři: Lauwaert, Johan, Van Puyvelde, Lisanne, Lauwaert, Jeroen, Thybaut, Joris W., Khelifi, Samira, Burgelman, Marc, Pianezzi, Fabian, Tiwari, Ayodhya N., Vrielinck, Henk
Médium: Journal Article
Jazyk:angličtina
Vydáno: Amsterdam Elsevier B.V 01.05.2013
Elsevier
Témata:
Applied sciences
Capacitance
Capacitance spectroscopy
CIGS
CIGS solar cells
Differential equations
Direct energy conversion and energy accumulation
Electrical engineering. Electrical power engineering
Electrical power engineering
Energy
Exact sciences and technology
MATHEMATICAL ANALYSIS
Mathematical models
Natural energy
Photoelectric conversion
Photovoltaic cells
Photovoltaic conversion
Solar cells
Solar cells. Photoelectrochemical cells
Solar energy
Spectroscopy
THIN FILMS
Time constant
Capacitance spectroscopy
CIGS solar cells
Cadmium sulfide solar cells
Ohmic contact
Absorbent material
RC circuit
Differential equation
p n junction
Numerical method
Electrical model
Modeling
Molybdenum
Solar cell
Direct method
Time dependence
Thin film cell
Capacitance
Zinc oxide
Time constant
Room temperature
ISSN:0927-0248, 1879-3398
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Shrnutí:We report evidence for the identification of the capacitance transients detected at room temperature for thin-film photovoltaic cells with CIGS absorbers as an additional non-ohmic contact in the structure with a time constant larger than that of the solar cell p–n junction. The N1 signal was recently interpreted as a back contact barrier for which the RC-like time constant is smaller than the time constant of the junction. In this work we unite these experimental observations in one model. Since for a Mo/CIGS/CdS/ZnO solar cell several interfaces are connected in series, we introduce the idea of modeling capacitance spectroscopy signals based on RC-circuits in series for each interface. It is shown that the distinct features observed in capacitance spectroscopy of CIGS solar cells can be mimicked using this circuit as an electrical model. The differential equation for this structure as a function of time is solved numerically. It is inherent to the model that the transients in such a structure are voltage transients over each of the interfaces and that the transients are coupled. These findings question the practical use of capacitance spectroscopy for direct measurement of defects in the absorber layer. ► We show that the transients at room temperature in CIGS originate from an RC-contact. ► We model DLTS and AS signals based on RC-circuits. ► We question the use of DLTS or AS for direct observation of defects.
Bibliografie:ObjectType-Article-1
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ISSN:0927-0248
1879-3398
DOI:10.1016/j.solmat.2013.01.014