scholarly journals Influence of Molybdenum Back Contact on the PID Effect for Cu(In,Ga)Se2 Solar Cells

Coatings ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 794 ◽  
Author(s):  
Oliver Salomon ◽  
Wolfram Hempel ◽  
Oliver Kiowski ◽  
Erwin Lotter ◽  
Wolfram Witte ◽  
...  
Keyword(s):  
Solar Cells ◽  
Glass Substrate ◽  
Optical Emission ◽  
Soda Lime ◽  
Deposition Process ◽  
Window Layer ◽  
Soda Lime Glass ◽  
Back Contact ◽  
Doping Density ◽  
Soda Lime Glass Substrate

The authors investigated the effect of an applied high voltage (1 kV) across the thickness of a soda-lime glass substrate of Cu(In,Ga)Se2 (CIGS) thin-film solar cells. Two types of CIGS cells were tested, differing only in the deposition process of the molybdenum (Mo) back contact. Whilst one cell type was susceptible to potential induced degradation (PID), the other exhibited highly increased stability against PID. PID occurs for PID-susceptible cells after the transfer of a certain amount of charge through the soda-lime glass substrate when the Mo back contact of the cell operates as a cathode (negatively biased versus backside of the substrate). Capacitance–voltage and electron-beam-induced current measurements showed an enlarged space charge region expanding to the Mo back contact and a lowered doping density by a negative potential for PID-susceptible cells. Glow discharge optical emission spectroscopy (GDOES) revealed an accumulation of sodium (Na) in the solution-grown CdS buffer layer and a segregation on the surface of the ZnO:Al window layer for higher charges for PID-susceptible cells. Cells with increased PID immunity did not show an increase of Na for charges up to around 9 mC/cm². We demonstrate that it is possible to improve the PID stability of CIGS solar cells by modification of the molybdenum back contact.

Optical and Electrical Analyses of Thallium Sulphide Thin Films

2021 ◽  
Vol 14 (3) ◽  
pp. 249-253
Keyword(s):  
Thin Films ◽  
Solar Cells ◽  
Soda Lime ◽  
High Energy ◽  
Window Layer ◽  
Soda Lime Glass ◽  
Energy Band Gap ◽  
Thallium Chloride ◽  
Light Region ◽  
Silicon And Germanium

Abstract: In this paper, suitability of thallium sulphide films were investigated as an alternative to conventional silicon and germanium that were used as window layers in solar cells. Thin films were deposited on soda lime glass (SLG) substrates in a chemical bath containing Thallium Chloride (TlCl2) and Thiourea (NH2)2CS which was conditioned at 80 ºC for about 5 hours to deposit the films. Effects of annealing on the film samples at 300 ºC and 350 ºC were studied respectively by use of UV-VIS Avantes electrophotometer and Four-Point-Probe (FPP) machine in the light region with wavelength range from 200 nm to 1000 nm. The results obtained suggest that the thin films obtained are good materials for optoelectronics. The absorption spectra exhibited a relatively high energy band-gap. Materials of this nature are good for window layers which serve as passage to the absorber layer where needed charge carriers are produced. Keywords: Thin film, Thallium Sulphide, Window layer, Optoelectronics, Solar cells.

scholarly journals The Effect of Sputtering Parameters on the Film Properties of Molybdenum Back Contact for CIGS Solar Cells

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Peng-cheng Huang ◽  
Chia-ho Huang ◽  
Mao-yong Lin ◽  
Chia-ying Chou ◽  
Chun-yao Hsu ◽  
...  
Keyword(s):  
Solar Cells ◽  
Signal To Noise Ratio ◽  
Soda Lime ◽  
Structural Features ◽  
Main Peak ◽  
Soda Lime Glass ◽  
Adhesive Tape ◽  
Back Contact ◽  
Working Pressure ◽  
Glass Substrates

Molybdenum (Mo) thin films are widely used as a back contact for CIGS-based solar cells. This paper determines the optimal settings for the sputtering parameters for an Mo thin film prepared on soda lime glass substrates, using direct current (dc) magnetron sputtering, with a metal Mo target, in an argon gas environment. A Taguchi method with an L9orthogonal array, the signal-to-noise ratio, and an analysis of variances is used to determine the performance characteristics of the coating operation. The main sputtering parameters, such as working pressure (mTorr), dc power (W), and substrate temperature (°C), are optimized with respect to the structural features, surface morphology, and electrical properties of the Mo films. An adhesive tape test is performed on each film to determine the adhesion strength of the films. The experimental results show that the working pressure has the dominant effect on electrical resistivity and reflectance. The intensity of the main peak (110) for the Mo film increases and the full width at half maximum decreases gradually as the sputtering power is increased. Additionally, the application of an Mo bilayer demonstrates good adherence and low resistivity.

Slump Molding of Microchannel Arrays in Soda-Lime Glass for Bioanalytical Device Development

2014 ◽  
Vol 2 (4) ◽  
Author(s):  
Richard E. Billo ◽  
Paul A. Wilson ◽  
John W. Priest ◽  
Mario Romero-Ortega ◽  
Shannon R. Brunskill ◽  
...  
Keyword(s):  
Glass Substrate ◽  
High Speed ◽  
Chemical Reactivity ◽  
Soda Lime ◽  
Nerve Tissue ◽  
Mold Material ◽  
Soda Lime Glass ◽  
Molding Process ◽  
Soda Lime Glass Substrate ◽  
Lab On Chip

A slump molding process was developed to place microchannel geometries in a soda-lime glass substrate for a lab-on-chip bioanalytical device. The process was developed to overcome the biological and chemical reactivity associated with current polymer lab-on-a-chip substrates, and as an alternative to using more expensive glass material. A high speed micro mill and UV laser micromachining center were used to fabricate the negative geometries in the graphite mold material that was used. The slumping process of the soda-lime glass was done using a glass kiln. Microchannel dimensions were in the mesa scale range of 50 μm width × 10 μm depth. The heating schedule for slump molding of the soda-lime glass to take its final shape to these dimensions was determined and documented. The functionality of the slumping process and resultant soda-lime glass device was validated through murine nerve tissue experiments conducted through the bioanalytical device that was developed. The research represented a novel use of slump molding, a process traditionally known for producing artistic works for: (a) embossing engineered microchannels and (b) reliably processing a soda-lime glass substrate, a material known to be difficult to work with due to its poor physical properties.

scholarly journals Characteristics of Bilayer Molybdenum Films Deposited Using RF Sputtering for Back Contact of Thin Film Solar Cells

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Sea-Fue Wang ◽  
Hsiao-Ching Yang ◽  
Chien-Fong Liu ◽  
Huy-Yun Y. Bor
Keyword(s):  
Solar Cells ◽  
Rf Sputtering ◽  
Bottom Layer ◽  
Soda Lime ◽  
Soda Lime Glass ◽  
Deposition Condition ◽  
Metal Contacts ◽  
Working Pressure ◽  
Soda Lime Glass Substrate ◽  
Sputtering Power

Mo films prepared under a single deposition condition seldom simultaneously obtain a low resistivity and a good adhesion necessary for use in solar cells. In order to surmount the obstacle, bilayer Mo films using DC sputtering at a higher working pressure and a lower working pressure have been attempted as reported in the literature. In this study, RF sputtering with different powers in conjunction with different working pressures was explored to prepare bilayer Mo film. The first bottom layer was grown at a RF sputtering power of 30 W and a working pressure of 12 mTorr, and the second top layer was deposited at 100 W and 4.5 mTorr. The films revealed a columnar growth with a preferred orientation along the (110) plane. The bilayer Mo films reported an electrical resistivity of 6.35 × 10−5 Ω-cm and passed the Scotch tape test for adhesion to the soda-lime glass substrate, thereby qualifying the bilayer Mo films for use as back metal contacts for CIGS substrates.

scholarly journals Optimization of Mo/Cr bilayer back contacts for thin-film solar cells

2018 ◽  
Vol 9 ◽  
pp. 2700-2707 ◽  
Author(s):  
Nima Khoshsirat ◽  
Fawad Ali ◽  
Vincent Tiing Tiong ◽  
Mojtaba Amjadipour ◽  
Hongxia Wang ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Solar Cell ◽  
Single Layer ◽  
Soda Lime ◽  
Thin Film Solar Cells ◽  
Soda Lime Glass ◽  
Tin Sulfide ◽  
Back Contact ◽  
Bilayer Films

Molybdenum (Mo) is the most commonly used material as back contact in thin-film solar cells. Adhesion of Mo film to soda–lime glass (SLG) substrate is crucial to the performance of solar cells. In this study, an optimized bilayer structure made of a thin layer of Mo on an ultra-thin chromium (Cr) adhesion layer is used as the back contact for a copper zinc tin sulfide (CZTS) thin-film solar cell on a SLG substrate. DC magnetron sputtering is used for deposition of Mo and Cr films. The conductivity of Mo/Cr bilayer films, their microstructure and surface morphology are studied at different deposition powers and working pressures. Good adhesion to the SLG substrate has been achieved by means of an ultra-thin Cr layer under the Mo layer. By optimizing the deposition conditions we achieved low surface roughness, high optical reflectance and low sheet resistivity while we could decrease the back contact thickness to 600 nm. That is two thirds to half of the thickness that is currently being used for bilayer and single layer back contact for thin-film solar cells. We demonstrate the excellent properties of Mo/Cr bilayer as back contact of a CZTS solar cell.

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