A highly efficient and stable CdTe/CdS thin film solar cell

Romeo, N.; Bosio, A.; Tedeschi, R.; Romeo, Alessandro; Canevari, V.

doi:10.1016/s0927-0248(98)00204-9

Cited by 184 publications

(90 citation statements)

References 13 publications

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“…The CdCl 2 solution was prepared with varying concentrations and with methanol or water [4] as the solvent. Some researchers deposited solid CdCl 2 layers on top of CdTe surfaces using many different techniques such as vacuum evaporation [43], and in some cases CdCl 2 layer thickness was comparable to that of CdTe layer [44]. Literature also shows the use of Freon gas (CHF 2 Cl) to introduce Cl and F during post growth heat treatment of CdTe layer [45].…”

Section: Post-growth Heat Treatmentmentioning

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: Post-growth Heat Treatmentmentioning

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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“…However, a PVD-deposited Sb buffer layer with Mo metallization has yielded high efficiency and low degradation in long-term performance. 163 Best cell stabilities have been achieved with RF-sputtered Sb 2 Te 3 buffer layer with Mo metallization as introduced by N. Romeo et al 165 Further, with Sb 2 Te 3 deposited by PVD and ED, the positive influence on the solar cell stability has been reconfirmed. 163,164 Long-term stability data for different buffer layer/metallization combinations obtained by light-soaking at elevated temperatures are shown in Figure 7.…”

Section: Cdtementioning

confidence: 99%

Development of thin‐film Cu(In,Ga)Se₂ and CdTe solar cells

Romeo¹,

Terheggen²,

Abou‐Ras³

et al. 2004

Progress in Photovoltaics

354

192

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Cu(In,Ga)Se2 and CdTe heterojunction solar cells grown on rigid (glass) or flexible foil substrates require p‐type absorber layers of optimum optoelectronic properties and n‐type wide‐bandgap partner layers to form the p–n junction. Transparent conducting oxide and specific metal layers are used for front and back electrical contacts. Efficiencies of solar cells depend on various deposition methods as they control the optoelectronic properties of the layers and interfaces. Certain treatments, such as addition of Na in Cu(In,Ga)Se2 and CdCl2 treatment of CdTe have a direct influence on the electronic properties of the absorber layers and efficiency of solar cells. Processes for the development of superstrate and substrate solar cells are reviewed. Copyright © 2004 John Wiley & Sons, Ltd.

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“…Cadmium sulfide (CdS) thin films have been used for CdS/ CdTe and CdS/CuInSe 2 solar cells [1][2][3][4]. CdS thin films are prepared by vacuum evaporation [2,4], sputtering [1,5], screen printing [4], chemical spray [6], and chemical bath deposition (CBD) [2][3][4]7].…”

Section: Introductionmentioning

confidence: 99%

“…CdS thin films are prepared by vacuum evaporation [2,4], sputtering [1,5], screen printing [4], chemical spray [6], and chemical bath deposition (CBD) [2][3][4]7]. The CBD method is based on a controlled precipitation of the material in such a way that the precipitation occurs uniformly onto the substrate [7].…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence of Nanocrystalline CdS Thin Films Prepared by Chemical Bath Deposition

Park¹

2010

Transactions on Electrical and Electronic Materials

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Nanocrystalline cadmium sulfide (CdS) thin films were prepared using chemical bath deposition in a solution bath containing CdSO 4 , SC(NH 2 ) 2 , and NH 4 OH. The CdS thin films were investigated using X-ray diffraction (XRD), photoluminescence (PL), and Fourier transform infrared spectroscopy (FTIR). The as-deposited CdS thin film prepared at 80°C for 60 min had a cubic phase with homogeneous and small grains. In the PL spectrum of the 2,900 Å-thick CdS thin film, the broad red band around 1.7 eV and the broad high-energy band around 2.7 eV are attributed to the S vacancy and the band-to-band transition, respectively. As the deposition time increases to over 90 min, the PL intensity from the band-to-band transition significantly increases. The temperature dependence of the PL intensity for the CdS thin films was studied from 16 to 300 K. The E A and E B activation energies are obtained by fitting the temperature dependence of the PL intensity. The E A and E B are caused by the deep trap and shallow surface traps, respectively. From the FTIR analysis of the CdS thin films, a broad absorption band of the OH stretching vibration in the range 3,000-3,600 cm -1 and the peak of the CN stretching vibration at 2,000 cm -1 were found.

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A highly efficient and stable CdTe/CdS thin film solar cell

Cited by 184 publications

References 13 publications

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

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

Development of thin‐film Cu(In,Ga)Se₂ and CdTe solar cells

Photoluminescence of Nanocrystalline CdS Thin Films Prepared by Chemical Bath Deposition

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A highly efficient and stable CdTe/CdS thin film solar cell

Cited by 184 publications

References 13 publications

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

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

Development of thin‐film Cu(In,Ga)Se2 and CdTe solar cells

Photoluminescence of Nanocrystalline CdS Thin Films Prepared by Chemical Bath Deposition

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Development of thin‐film Cu(In,Ga)Se₂ and CdTe solar cells