Polycrystalline CdTe thin films for photovoltaic applications

Bosio, A.; Romeo, N.; Mazzamuto, S.; Canevari, V.

doi:10.1016/j.pcrysgrow.2006.09.001

Cited by 194 publications

(167 citation statements)

References 52 publications

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“…XRD analysis shows cubic (111) CdTe diffraction as the preferred orientation of all the CdTe explored in this work, while, the highest diffraction intensity were observed at 1360 mV under both as-deposited and CdCl 2 treated conditions. After CdCl 2 treatment, an improvement in the absorption edge slope was observed with the highest slope signifying highest CdTe quality [20,32] was observed at 1360 mV. Morphologically, better glass/FTO substrate coverage was observed at Cd-rich CdTe layer grown at 1400 mV while Te-rich layer grown at 1330 mV show high pinhole density.…”

Section: Resultsmentioning

confidence: 97%

“…As shown in Fig. 6, the growth of CdTe at 1360 mV shows the sharpest absorption edge which signifies superior CdTe layer [20], while the growth of CdTe layer away from 1360 mV shows a reduction in the slope of the optical absorption edge in both the as-deposited and CdCl 2 treated CdTe layers due to Cd-or Te-richness in CdTe. It should be noted that CdCl 2 treatment utilised in this work increases the sharpness of the absorption edge across all growth voltages explored.…”

Section: Optical Absorption Studymentioning

confidence: 89%

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Analysis of electrodeposited CdTe thin films grown using cadmium chloride precursor for applications in solar cells

Ojo

Dharmadasa

2017

J Mater Sci: Mater Electron

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Section: Resultsmentioning

confidence: 97%

Section: Optical Absorption Studymentioning

confidence: 89%

Analysis of electrodeposited CdTe thin films grown using cadmium chloride precursor for applications in solar cells

Ojo

Dharmadasa

2017

J Mater Sci: Mater Electron

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“…There are numerous studies on the CdCl 2 treatment of CdTe layers and both material changes and device improvements have been reported [35,[49][50][51]. Depending on the studies carried out, various changes such as (a) re-crystallisation and grain growth, (b) interactions at CdS/CdTe interface, (c) enhancement of lifetime of charge carriers, (d) passivation of grain boundaries and (e) enhancement of device efficiencies are reported in the literature [4,52].…”

Section: Summary Of Reported Results On Cdcl 2 Treatmentmentioning

confidence: 99%

“…XRD measurements show that (111) preferred orientation for CdTe grown by low temperature techniques like ED and sputtering. Literature also reports columnar growth of CdTe when other growth techniques are used [49,66]. This must be due to the natural preference of the FTO/CdTe or FTO/CdS/CdTe interfaces, or the preferred CdTe growth direction.…”

Section: Grain Boundary Enhanced Pv Effectmentioning

confidence: 99%

Unravelling complex nature of CdS/CdTe based thin film solar cells

Dharmadasa

Ojo

2017

J Mater Sci: Mater Electron

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and high-temperature growth techniques. The wide bandgap (E g = 2.42 eV) window material, CdS was mainly grown by chemical bath deposition (CBD) and narrow bandgap (E g = 1.45 eV) absorber material, CdTe was grown by over 14 different methods [1]. High efficiencies were achieved by the combination of CdS with CdTe layers grown by high temperature growth methods such as closed space sublimation (CSS) or close spaced vapour transport (CSVT) for a long period. Depending on the growth technique, material growth mechanisms, micro-structure and impurity inclusions are going to vary. Although there are a large number of publications reporting material characterisation, deep understanding is required on material issues such as defects and doping concentrations.The next area needing deeper understanding is the postgrowth chemical and heat treatment. The devices fabricated using as-made CdTe materials show poor device performance in the range ~(0-6)% depending on the growth technique used. However, from 1976 [2], the researchers were aware of the drastic improvement of the device performance after heat treatment around 450 °C in air, in the presence of CdCl 2 . This was known as "CdCl 2 treatment" and device efficiencies improved to mid-teens achieving good solar cell performance. Although there were tremendous efforts to explore the complexity of changes during this treatment, full understanding has not yet been achieved.The third main area of complexity comes from the CdTe/electrical back contact formation. It is essential to clean the CdTe surface after CdCl 2 treatment, and researchers were using different chemicals to clean the surface prior to metallisation. Various electrical contacts have been used to complete the devices and varying results have been reported in the literature [3]. Initial high efficiency, reproducibility and yield, stability and lifetime are main features of fully fabricated devices to establish. Some of these Abstract Thin film solar cells based on CdS/CdTe hetero-structure has shown a drastic improvement changing from 16.5 to 22.1% efficiency during a short period of time from ~2013 to ~2016. This has happened in the industrial environment and the open research in this field has stagnated over a period of two decades prior to ~2013. Most of the issues of this hetero-structure were not clear to the photovoltaic (PV) community and research efforts should be directed to unravel its complex nature. Issues related to materials, post-growth treatment, chemical etching prior to metallisation and associated device physics are the main areas needing deeper understanding in order to further develop this device. After a comprehensive research programme in both academia and in industry on these materials, surfaces and interfaces and fully fabricated devices over a period of over three decades by the main author, the current knowledge as understood today, on all above mentioned complex issues are presented in this paper. Full understanding of this structure will enable PV developers to further improve the ...

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“…CdTe in the shape of thin film can be polycrystalline or nanocrystalline, which can contribute towards the change of its characteristics [4]- [6]. Different methods are used for the preparation of thin films of CdTe, including electrodeposition [4], [7], [8], magnetron sputtering [9], [10], thermal evaporation [5], [11], close space sublimation [12] - [14] and others [15], [16].…”

Section: Introductionmentioning

confidence: 99%