Nanowire and core-shell-structures on flexible Mo Foil for CdTe solar cell applications

CdTe films, nanowires, film-nanowire combinations and CdS-CdTe core-shell structures have been fabricated in a preliminary survey of growth methods that will generate structures for PV applications. Selectivity between film, nanowire and film plus nanowire growth was achieved by varying the pressure of N2 gas present during Au-catalysed VLS growth of CdTe, on either Mo or Si substrates. Metamorphic growth of CdTe nanowires on sputtered CdTe films, deposited on glass substrates, was demonstrated. Coating of CdTe nanowires with CBD CdS gave conformal coverage whereas coating with MOCVD (Cd,Zn)S yielded highly crystallographic dendritic growth on the wires

High-fidelity simulations of CdTe vapor deposition from a new bond-order potential-based molecular dynamics method

CdTe has been a special semiconductor for constructing the lowest-cost solar cells and the CdTe-based Cd1-xZnxTe alloy has been the leading semiconductor for radiation detection applications. The performance currently achieved for the materials, however, is still far below the theoretical expectations. This is because the property-limiting nanoscale defects that are easily formed during the growth of CdTe crystals are difficult to explore in experiments. Here we demonstrate the capability of a bond order potential-based molecular dynamics method for predicting the crystalline growth of CdTe films during vapor deposition simulations. Such a method may begin to enable defects generated during vapor deposition of CdTe crystals to be accurately explored

Defect tolerance in as-deposited selenium-alloyed cadmium telluride solar cells

The efficiency of cadmium telluride (CdTe) solar cells is limited primarily by voltage, which is known to depend on the carrier concentration and carrier lifetimes within the absorber layer of the cell. Here, cathodoluminescence measurements are made on an as-deposited CdSeTe/CdTe solar cell that show that selenium alloyed CdTe material luminesces much more strongly than non-alloyed CdTe. This reduction in non-radiative recombination in the CdSeTe suggests that the selenium gives it a certain defect tolerance. This has implications for carrier lifetimes and voltages in cadmium telluride solar cells

Stable Monolayer alpha-Phase of CdTe: Strain-Dependent Properties

CdTe is a well known and widely used binary compound for optoelectronic applications. In this study, we propose the thinnest, free standing monolayer of CdTe which holds the tetragonal-PbO (alpha-PbO) symmetry. The structural, electronic, vibrational and strain dependent properties are investigated by means of first principles calculations based on density functional theory. Our results demonstrate that the monolayer alpha-CdTe is a dynamically stable and mechanically flexible material. It is found that the thinnest monolayer crystal of CdTe is a semiconductor with a direct band gap of 1.95 eV, which corresponds to red light in the visible spectrum. Moreover, it is found that the band gap can be tunable under biaxial strain. With its strain-controllable direct band gap within the visible spectrum, stable alpha-phase of monolayer CdTe is a suitable candidate for optoelectronic device applications

First principles study of Bi dopen CdTe thin film solar cells: electronic and optical properties

Nowadays, efficiency improvement of solar cells is one of the most important issues in photovoltaic systems and CdTe is one of the most promising thin film photovoltaic materials we can found. CdTe reported efficiencies in solar energy conversion have been as good as that found in polycrystalline Si thin film cell [1], besides CdTe can be easily produced at industrial scale

Stable Ultra-thin CdTe Crystal: A Robust Direct Gap Semiconductor

Employing density functional theory based calculations, we investigate structural, vibrational and strain-dependent electronic properties of an ultra-thin CdTe crystal structure that can be de- rived from its bulk counterpart. It is found that this ultra-thin crystal has an 8-atom primitive unit cell with considerable surface reconstructions. Dynamic stability of the structure is predicted based on its calculated vibrational spectrum. Electronic band structure calculations reveal that both electrons and holes in single layer CdTe possess anisotropic in-plane masses and mobilities. Moreover, we show that the ultra-thin CdTe has some interesting electromechanical features, such as strain-dependent anisotropic variation of the band gap value, and its rapid increase under per- pendicular compression. The direct band gap semiconducting nature of the ultra-thin CdTe crystal remains unchanged under all types of applied strain. With a robust and moderate direct band gap, single-layer CdTe is a promising material for nanoscale strain dependent device applications

Electro-optic characteristics of CdTe at 3.39 and 10.6 µ

The physical characteristics of high resistivity CdTe which are relevant to its use for electro-optic modulation have been investigated at 3.39 and 10.6 µ. The unclamped electro-optic characteristic n0^3r41 of CdTe was found to be 12 × 10^–11 m/V and the absorption coefficient is 0.006 cm^–1. Our measurements indicate that CdTe will be a very important material for electro-optic modulation in the infrared

Investigation of thin film solar cells on CdS/CdTe base with different back contacts

The peculiarities of photo-electric processes in thin film CdS/CdTe solar cells (SC) with different back electrodes (Cu/Au, ITO, Cu/ITO) havebeen studied. As it was established by capacitance – voltage (C-V) characteristics, the potential barrier heights for CdTe/Cu/Au and CdTe/ITO were 0.3 eV and 2.2 eV, respectively. The concentrations of charge carriers near back contact consisted 9⋅10²⁰ m⁻³ and 2⋅10²¹ m⁻³, respectively. A high carrier concentration and hi gh potential barrier of the ITO back contact caused the tunnel – recombination mechanism of the charge transport. The investigations of CdS/CdTe/ITO SC spectral photosensitivity testify a negative impact of the developed grain-boundary surface of the base layer on the processes of diffusion and separation of non-equilibrium currentcarriers generated by short-wave radiation. It is shown that the deposition of Cu nanolayer before the deposition of ITO films give stable efficiency 10% for bifacial CdS/CdTe solar cells