Self-consistent simulation of CdTe solar cells with active defects

Brinkman, Daniel; Guo, Di; Akis, R.; Ringhofer, Christian; Sankin, Igor; Fang, Tong; Vasileska, Dragica

doi:10.1063/1.4927155

Cited by 13 publications

(3 citation statements)

References 42 publications

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“…The developed software package used in this study consists of two stand‐along blocks: a .NET‐based graphical user interface (GUI) and a MATLAB‐based “numerical engine.” The GUI block is responsible to define simulated structure, properties of materials, lattice sites, defect species and reactions. The numerical engine transfers the GUI inputs into a matrix form and solves the system of reaction‐diffusion equations (Equation ) using algorithms proposed by Brinkman et al This part is written using finite‐volume method for rectilinear grid to solve Equation in two dimensions. Note that the method can also accommodate 1‐ and 0‐D problems by setting number of volumes to unity in one or both dimensions, correspondingly.…”

Section: Methodsmentioning

confidence: 99%

Kinetic Simulations of Cu Doping in Chlorinated CdSeTe PV Absorbers

Sankin

Krasikov

2019

Physica Status Solidi (a)

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This paper reports on 1D kinetic modeling of p‐type doping formation in Cu‐doped chlorinated CdSeTe photovoltaic (PV) absorbers with graded Se profiles. Following the recent progress in kinetic simulations of the defect chemistry in stoichiometric CdTe films, this work extends simulation capabilities to a domain of semiconductor alloy films with graded stoichiometries. The defect formation energies and ionization levels, as well as the diffusion and reaction barriers used in the reaction‐diffusion equations are calculated from the first principles. A new formalism is employed to account for the uncertainty of the defect formation energies in semiconductor alloys caused by unknown local surrounding. The developed methodology is used to model a practical fabrication process of p‐type doping formation in graded CdSeTe absorbers and to study the effect of alloy stoichiometry on the doping activation.

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Section: Methodsmentioning

confidence: 99%

Kinetic Simulations of Cu Doping in Chlorinated CdSeTe PV Absorbers

Sankin

Krasikov

2019

Physica Status Solidi (a)

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“…Recent development of low-temperature time-resolved photoluminescence shows strong potential to estimate the concentration and ionization energy of Cu Cd acceptors in CdTe [37]. On the other hand, a 2D simulation scheme that takes grain boundary effects (including diffusion, reaction and segregation of point defects related to grain boundary) into consideration [38] could also verify the role of GBs in general.…”

Section: Model 1: Consider Knock-off Reaction Onlymentioning

confidence: 99%

Metastability and reliability of CdTe solar cells

Guo

Brinkman

Shaik

et al. 2018

J. Phys. D: Appl. Phys.

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Thin-film modules of all technologies often suffer from performance degradation over time. Some of the performance changes are reversible and some are not, which makes deployment, testing, and energy-yield prediction more challenging. Manufacturers devote significant empirical efforts to study these phenomena and to improve semiconductor device stability. Still, understanding the underlying reasons of these instabilities remains clouded due to the lack of ability to characterize materials at atomistic levels and the lack of interpretation from the most fundamental material science. The most commonly alleged causes of metastability in CdTe devices, such as ‘migration of Cu’, have been investigated rigorously over the past fifteen years. Still, the discussion often ended prematurely with stating observed correlations between stress conditions and changes in atomic profiles of impurities or CV doping concentration. Multiple hypotheses suggesting degradation of CdTe solar cell devices due to interaction and evolution of point defects and complexes were proposed, and none of them received strong theoretical or experimental confirmation. It should be noted that atomic impurity profiles in CdTe provide very little intelligence on active doping concentrations. The same elements could form different energy states, which could be either donors or acceptors, depending on their position in crystalline lattice. Defects interact with other extrinsic and intrinsic defects; for example, changing the state of an impurity from an interstitial donor to a substitutional acceptor often is accompanied by generation of a compensating intrinsic interstitial donor defect. Moreover, all defects, intrinsic and extrinsic, interact with the electrical potential and free carriers so that charged defects may drift in the electric field and the local electrical potential affects the formation energy of the point defects. Such complexity of interactions in CdTe makes understanding of temporal changes in device performance even more challenging and a closed solution that can treat the entire system and its interactions is required.

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“…A fully implicit reaction scheme is applied for each pair of reactions to maintain the conservation of total atoms. Detailed derivation and numerical solutions of the diffusion-reaction equations is beyond the scope of this paper and can be found in [28].…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Copper Migration in Single Crystal CdTe

Guo

Fang

Moore

et al. 2016

IEEE J. Photovoltaics

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Absorber material with high and stable p-type doping that does not impede free carrier lifetime is the key component enabling efficiency and stability improvements in thin-film CdTe technology. To better understand the compensation mechanism and the metastable effects related to Cu acceptors, the most common p-type dopant in CdTe, i.e., a detailed kinetic model describing the behavior of intrinsic and Cu-related defects in this material, has been developed and applied for the first time. Migration and reactions of these point defects in single crystal CdTe have been investigated by solving diffusion-reaction equations in the time-space domain self-consistently with free carrier transport. The simulation results supported by reasonable match to experimental data have shed light on the nature of limited Cu incorporation (also known as the Cu solubility limits) and Cu self-compensation during the annealing and cooling processes.

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Self-consistent simulation of CdTe solar cells with active defects

Cited by 13 publications

References 42 publications

Kinetic Simulations of Cu Doping in Chlorinated CdSeTe PV Absorbers

Kinetic Simulations of Cu Doping in Chlorinated CdSeTe PV Absorbers

Metastability and reliability of CdTe solar cells

Numerical Simulation of Copper Migration in Single Crystal CdTe

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