Properties of CdTe solar cells electrochemically prepared from single crystals

Abstract

Optoelectrical properties of junctions electrochemically formed on the surface of n‐type CdTe single crystals are reported. The carrier transport process across the junction is controlled by tunnelling through the barrier from one side and by thermal emission followed by recombination at interface states from the opposite side of the junction. The CU characteristics have the shape typical for abrupt junctions and the built‐in potential UD = 1.1 V confirms the formation of an np homojunction covered by a thin Te film. The photovoltaic parameters of these cells are: open‐circuit voltage 0.42 V short‐circuit current density 0.5 to 0.8 mA/cm2, and fill factor 0.54. The spectral response indicate that the thin layer of Te acts only as an optical filter.

Syntheses, Crystal and Band Structures, and Magnetic and Optical Properties of New CsLnCdTe3 (Ln = La, Pr, Nd, Sm, Gd−Tm, and Lu)

“…Binary CdTe is an useful material that has been widely studied because of its possible applications as solar cells, − photovoltaic devices, − light-emitting diodes, − semiconductor detectors, − and thermoelectric materials. − Although CdTe has shown excellent performance as a solar cell material owing to its optimal energy gap, it also has some problems, such as a large absorption coefficient, native defects, electrical contacts, and highly rapid recombination of ions on the surface of CdTe homojunction, that reduce the efficiency of the solar cell. − To overcome these specific problems, two main approaches have been developed to synthesize desirable semiconductor materials: (1) By synthesizing nanoscale materials, the size of CdTe is reduced (e.g., quantum dots and quantum wells), which results in the change of their chemical and physical properties as compared with the bulk material; some examples include the increase of the band gap energy, the decrease of melting point, and the enhancement of photocatalytic properties. − This method can alter the energy gap by confining the particle size, which leads to the disruption of the 3D bonding networks in the bulk entity. − (2) Utilizing the chemical synthesis approaches, many new materials based on CdTe with main-group metals, ,− transition metals, − and rare-earth metals ...…”

EC-STM Studies of Te and CdTe Atomic Layer Formation from a Basic Te Solution

“…6,7 Te in particular, as a constituent of CdTe, is an important optoelectronic material. 8,9 Compound semiconductors are typically electrodeposited from a single bath, containing precursors for all the constituent elements, in a process referred to as codeposition. More recently, a number of Te-containing compounds, such as CdTe, have been electrodeposited using a method referred to as electrochemical atomic layer epitaxy ͑EC-ALE͒.…”

“…Te UPD on Au from acidic electrolytes has been studied previously using EC-scanning tunneling microscopy ͑STM͒. 8,9,16,17 Several structures have been observed on Au͑111͒, including a 1/3 coverage (ͱ3 ϫ ͱ3)R30°-Te with (13 ϫ 13) light domain walls, a 4/11 coverage (ͱ7 ϫ ͱ13), and a 4/9 coverage (3 ϫ 3)-Te. The formation of the (3 ϫ 3)-Te adlayer coincided with a surface roughening transition.…”

A comparison of the physical properties of CdTe single crystal and thin film

“…The theoretical maximum solar cell efficiency of 24.2% requires the use of a material with an energy gap of 1.63 eV [1]; the direct gap of ∼1.5 eV of CdTe [2,3] is close to this value. Solar cell efficiencies greater than 10% have been achieved with CdTe single crystals [4]. Photoconductivity in II-VI compounds is an important indicator of crystal quality, since it can provide valuable information about the type and distribution of defects in a crystal [2].…”