摘要:

The basic physical aspects of the CdTe-thin film solar cell in its various embodiments are reviewed. Deposition techniques are briefly described, results of present pilot-line production efforts and the future potential are discussed, which make the CdTe thin film solar cell a promising candidate for low cost and well-above 10% module-efficiency. A detailed costing model for thin film solar cells is presented illustrating that low cost of around 0.9 ECU/Wpwill be achievable upon suitable upscaling of production.

ISSN:0142-5919    

DOI:10.1080/01425919208909746

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Recent progress in CdTe solar cells is summarized through quantitative comparison of individual loss mechanisms in high-efficiency cells from nine laboratories that collectively used seven different CdTe deposition techniques. The highest value of Vαhas increased, and there have been significant reductions in window absorption, diode quality factor under illumination, series resistance, and reflection. Among the manufacturers, one finds substantial variations in which losses are dominant. If the smallest individual losses were combined into a single cell, its efficiency would exceed 17%.

ISSN:0142-5919    

DOI:10.1080/01425919208909747

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

High efficiency solar cells can be fabricated on CdTe films prepared by a wide variety of deposition techniques. Most of these methods yield CdTe layers that need to be subjected to post-deposition treatments before they can be utilized in high efficiency device fabrication. In some cases these treatments can be made an integral part of the film growth process so that a post-deposition step is not needed. This paper discusses the procedures that are commonly used in high efficiency CdTe solar cell fabrication and reports on a newly emerging technique that holds the promise of becoming a high-throughput industrial process for thin film photovoltaic module production.

ISSN:0142-5919    

DOI:10.1080/01425919208909748

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Efficiency limiting mechanisms associated with CdS substrates, CdCl2 treated CdTe films, and Cu/Au contacts were investigated. It was found that heat treatment of CdS in hydrogen ambient prior to CdTe deposition removed the oxygen related defects from the CdS films, but created Cd deficient CdS surface, resulting in an optimum temperature of 450°C. Growth of CdTe films on the CdS under Te-rich conditions enhanced the interdiffusion between CdTe and CdS and reduced the CdTe bandgap to 1.47eV, whereas, growth of CdTe films under Cd-rich conditions retained the CdTe bandgap at 1.5 eV. CdCl2 treatment on CdTe improved the cell performance significantly by virtue of grain growth, reduced leakage current, and change in carrier transport mechanism. However, it also produced defects at Eν + 0.64 and Eν + 0.17 eV due to VCd-Cl complexes. An inverse correlation was found between the density of these defects and V ∞ Finally, a rapid initial degradation was observed in the higher efficiency (10-12%) CdTe cells with Cu/Au contacts but a bromine-methanol etch was found to restore the cell performance.

ISSN:0142-5919    

DOI:10.1080/01425919208909749

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Ann-CdS/p-CdTe solar cell module constructed by complete seal of solar cell formed on a glass substrate by screen-printing and sintering process, was subjected to a heavy sunshine weather-meter test. The conversion efficiency of the module began to degrade after 50 days. Chemical analyses on gases in the sealed module showed that decrease in oxygen down to 2 vol.% had caused the degradation. Inversely, when sufficient oxygen was supplied to the solar cell by breaking the seal, the efficiency recovered up to its initial value within several days even at room temperature. Estimation of reaction velocity at room temperature suggested that the present recovery phenomenon was the same as increase inp-type characteristics by heat treatment in air in other fabrication process of CdS/CdTe junction. Easiness and reversibility of transformation from oxygen deficient to sufficient states in CdTe, strongly suggest that oxygen in CdTe induces a single acceptor which was confirmed in oxygen doped ZnSe.

ISSN:0142-5919    

DOI:10.1080/01425919208909750

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Screen printed and sintered CdTe-CdS solar cells differ in some aspects from other CdTe cells: the layers are thicker, the fabrication temperatures higher, the grain size is usually better. A good morphology, a good junction behaviour and consequently a high open circuit voltage, and efficient doping of the CdTe are seen to be an inherent advantage of the screen printing and sintering technology. On the other hand, care has to be taken to avoid strong interdiffusion and optical transmission loss in the CdS window.

ISSN:0142-5919    

DOI:10.1080/01425919208909751

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Large area 300 mm x 300 mm CdS/CdTe solar cells with record efficiencies over 10% have been fabricated using a reproducible, safe and low cost electrodeposition route for CdTe deposition. CdS window layers have been grown using chemical bath deposition which produces uniform adherent films by a cost effective route. Electrical characterization of small area (0.02 cm2) devices confirms that the structure is p-n rather than p-i-n. Module reliability tests show efficiency stability for more than 16,000 hours outside, and very little change using indoor environmental tests.

ISSN:0142-5919    

DOI:10.1080/01425919208909752

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Solar cells with a nCdS/pCdTe heterojunction have been fabricated from elcctrodepositcd CdS and CdTe layers. Sets of cells were made with CdTe films deposited at a range of potentials (QRP) from solutions in which the concentrations of cadmium and of tellurium ions were systematically varied. The properties of the CdTe films and of the cells were examined. The range of values over which suitable solar cells could be made was determined for a given set of processing conditions. The most efficient solar cells were obtained under those processing conditions for solutions with cadmium ion 2.5 M and tellurium ions 120 ppm deposited in a range of QRP's of 20—40 mV (relative to a saturated calomel reference electrode). Morphological studies showed that the most efficient cells had (he largest grain size. Electrical and capacitance measurements showed that the major losses in the solar cell parameters increased with increased polycrystalline structure.

ISSN:0142-5919    

DOI:10.1080/01425919208909753

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

An area of major importance relating to prototype developments in the photovoltaic field is accurate measurement of photovoltaic devices and modules. In this paper are described some measurement irregularities that can affect performance testing of CdS/CdTe devices and modules, and therefore can affect life testing and technical developmental decisions. These irregularities are dependent on the material being tested and on the measurement technique. They especially relate to devices filled with deep-level traps (large diode ideality factors) that can result in an inability to instantaneously equilibrate to an existing or changing bias condition.

ISSN:0142-5919    

DOI:10.1080/01425919208909754

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Cadmium telluride is a most promising thin film photovoltaic material as shown by the higher than 10% efficient CdS/CdTe heterojunction solar cells. In this work, thin film CdS/CdTe solar cells have been prepared using CdS films grown from an aqueous solution and p-CdTe films deposited by metalorganic chemical vapor deposition (MOCVD) and close-spaced sublimation (CSS). The solution-grown CdS films, with high photoconductivity ratios and good optical transmission, are well-suited for optoelectronic devices. The CdTe films deposited by CSS show considerably better microstructure than those by MOCVD because of the higher substrate temperature used in the CSS process. The properties of CdS/CdTe heterojunctions have been studied. Solar cells of 1 cm2 with an AM 1.5 efficiency of 14.6%, verified at the National Renewable Energy Laboratory, have been CdTe films

ISSN:0142-5919    

DOI:10.1080/01425919208909755

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor