Kesterite Inorganic-Organic Heterojunction for Solution Processable Solar Cells

Though Cu2ZnSnS4 (CZTS) is a promising material for thin film solar cells, a significant challenge remains in understanding the structures being formed, particularly in non-stoichiometric materials. We use the extended x-ray absorption fine structure (EXAFS) technique to study the local structure and stoichiometry of as-made, Cu-deficient, CZTS nanoparticles and present K edge data and fits about each of the cations (Cu, Zn, Sn). The data show that all the metal-S (M-S) pairs have the bond lengths of the kesterite structure within 0.02Å, and the pair distribution function is very narrow (σ ∼ 0.07Å). This precludes significant fractions of other phases with different M-S bondlengths. The data also reveal some Sn second neighbors about Sn whereas there are none in the stoichiometric kesterite (or stannite) structure. Consequently, Sn antisite defects must be present on Cu or Zn sites; this is not surprising since there is some excess of Sn. More importantly, the second neighbor Sn-Sn distance is significantly longer than other M-M distances and the antisite Sn defects must therefore introduce significant disorder within the Cu and Zn sub-lattices. The largest distortions are found about Cu and are modeled using a strongly broadened (or split) peak distribution for the Cu-Cu/Zn pairs. We also find that excess Zn does not go onto Cu sites but rather onto Sn sites. The samples are best described as a kesterite structure with significant antisite disorder.

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“…14 and also Data et al 36 . Thus it is not clear how they obtained detailed fits of the Cu-metal and Zn-metal peaks.…”

Section: Discussionmentioning

confidence: 99%

“…Data et al 36 also carried out EXAFS measurements on nanoparticles, presumably at 300K, and find considerable disorder for the further neighbor shells. Their metal-S distances agree with our results within 0.01Å, but they provide no analysis for the further neighbors.…”

Section: Discussionmentioning

confidence: 99%

Local Structure Studies of As-Made Cu2ZnSnS4 Nanoparticles

et al. 2017

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“… To measure the onset potential, mark the tangent line to the CV peak ( Figure 3 ). Calculate the desired values from the onset potential of the reduction or oxidation process using equations ( Equations 1 and 2 ) 10 18 19 36 37 38 . (1) where is the onset of the oxidation potential calibrated with ferrocene * (2) where is the onset of the reduction potential calibrated with ferrocene * * Potential calibrated with ferrocene means that the value of potential from the measurement is reduced by the oxidation potential of ferrocene.…”

Section: Protocolmentioning

confidence: 99%

“…For organic photovoltaics (OPVs) 3 4 as well as organic field effect transistors (OFETs) 5 6 , it is necessary to have materials with high charge carrier mobility. In addition to the analysis of charge carriers, several important parameters of organic electroactive materials help in predicting where the material could be used: ionization potential (IP), electron affinity (EA) energy levels, and band-gap between them 7 8 9 10 .…”

Section: Introductionmentioning

confidence: 99%

Using Cyclic Voltammetry, UV-Vis-NIR, and EPR Spectroelectrochemistry to Analyze Organic Compounds

Pluczyk¹,

Vasylieva²,

Data³

2018

JoVE

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Cyclic voltammetry (CV) is a technique used in the analysis of organic compounds. When this technique is combined with electron paramagnetic resonance (EPR) or ultraviolet-visible and near-infrared (UV-Vis-NIR) spectroscopies, we obtain useful information such as electron affinity, ionization potential, band-gap energies, the type of charge carriers, and degradation information that can be used to synthesize stable organic electronic devices. In this study, we present electrochemical and spectroelectrochemical methods to analyze the processes occurring in active layers of an organic device as well as the generated charge carriers.

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“…Like every method, CV is not perfect and to increase the applicability and quality of results, the connection with another spectroscopic technique is important. We already present several investigations where the electrochemical impedance spectroscopy (EIS) technique was employed 14 15 16 but in this work, we intended to show step-by-step how to reinforce the CV technique by EIS.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Chulkin

Data

2018

JoVE

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Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). In the case of fast reversible electrochemical processes, current is predominantly affected by the rate of diffusion, which is the slowest and limiting stage. EIS is a powerful technique that allows separate analysis of stages of charge transfer that have different AC frequency response. The capability of the method was used to extract the value of charge transfer resistance, which characterizes the rate of charge exchange on the electrode-solution interface. The application of this technique is broad, from biochemistry up to organic electronics. In this work, we are presenting the method of analysis of organic compounds for optoelectronic applications.

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Kesterite Inorganic-Organic Heterojunction for Solution Processable Solar Cells

Cited by 9 publications

References 56 publications

Local Structure Studies of As-Made Cu2ZnSnS4 Nanoparticles

Local Structure Studies of As-Made Cu2ZnSnS4 Nanoparticles

Using Cyclic Voltammetry, UV-Vis-NIR, and EPR Spectroelectrochemistry to Analyze Organic Compounds

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

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