Dopant and impurity effects in electrodeposited CdS/CdTe thin films for photovoltaic applications

Dennison, Stephen

doi:10.1039/jm9940400041

Cited by 37 publications

(28 citation statements)

References 14 publications

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“…The main reason to remove the reference electrode from the 3-electrode system is to avoid contamination of detrimental group-I impurities such as K and Ag. Commercial reference electrodes have an outer jacket of saturated KCl solution, and leakage of any K ions into the electrolyte in ppb and ppm levels drastically reduces the efficiency of the CdS/CdTe solar cell, very similar to the effect of Na, Cu and Ag [34].…”

Section: Growth Of Cdte By Electrodepositionmentioning

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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Section: Growth Of Cdte By Electrodepositionmentioning

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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“…For this reason the cathodic voltage is recorded with respect to the reference electrode. However, it should be taken into consideration that reference electrodes such as Ag/AgCl and saturated calomel, contain Ag + and K + which contaminate the electrolyte by acting as detrimental impurity for devices [15,16]. These impurity ions can leak into the deposition electrolyte and drastically reduce the efficiency of fabricated solar cells based on CdTe.…”

Section: Introductionmentioning

confidence: 99%

Electrodeposition of CdTe thin films using nitrate precursor for applications in solar cells

Salim

Patel

Abbas

et al. 2015

J Mater Sci: Mater Electron

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“…The increase in demand for clean and sustainable energy is a huge challenge for the photovoltaic of impurities. Ag + ions and other group-I ions, such as Na + and K + , are highly poisonous to CdTe solar cells [21], and the removal of the reference electrode from the electrolyte could be highly beneficial for achieving high performance devices. Reference electrodes usually have a saturated KCl solution outer jacket in commercially available products with a possibility of leaking K + into the electrolyte.…”

Section: Introductionmentioning

confidence: 99%

Electroplating of CdTe Thin Films from Cadmium Sulphate Precursor and Comparison of Layers Grown by 3-Electrode and 2-Electrode Systems

et al. 2017

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Electrodeposition of CdTe thin films was carried out from the late 1970s using the cadmium sulphate precursor. The solar energy group at Sheffield Hallam University has carried out a comprehensive study of CdTe thin films electroplated using cadmium sulfate, cadmium nitrate and cadmium chloride precursors, in order to select the best electrolyte. Some of these results have been published elsewhere, and this manuscript presents the summary of the results obtained on CdTe layers grown from cadmium sulphate precursor. In addition, this research program has been exploring the ways of eliminating the reference electrode, since this is a possible source of detrimental impurities, such as K + and Ag + for CdS/CdTe solar cells. This paper compares the results obtained from CdTe layers grown by three-electrode (3E) and two-electrode (2E) systems for their material properties and performance in CdS/CdTe devices. Thin films were characterized using a wide range of analytical techniques for their structural, morphological, optical and electrical properties. These layers have also been used in device structures; glass/FTO/CdS/CdTe/Au and CdTe from both methods have produced solar cells to date with efficiencies in the region of 5%-13%. Comprehensive work carried out to date produced comparable and superior devices fabricated from materials grown using 2E system.

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Dopant and impurity effects in electrodeposited CdS/CdTe thin films for photovoltaic applications

Cited by 37 publications

References 14 publications

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

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

Electrodeposition of CdTe thin films using nitrate precursor for applications in solar cells

Electroplating of CdTe Thin Films from Cadmium Sulphate Precursor and Comparison of Layers Grown by 3-Electrode and 2-Electrode Systems

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