1 - Introduction

Nitrogen doped single layer graphene for CZTS-based thin film solar cells

Energy-related concerns about traditional resources include the depletion of fossil fuel, a dramatic increase in oil prices, the global warming effect caused by pollutant emissions from conventional energy resources, and the increase in the energy demand. These concerns have resulted in the recent remarkable growth of renewable energy industries [1-3]. Furthermore, renewable energy has become a significantly important research area for many researchers as well as for governments of many countries as they attempt to ensure the safety, long-term capability, and sustainability of the use of global alternative energy resources [2]. Renewable energy resources include solar, geothermal, wind, biomass, ocean, and hydroelectric energy. [4] In particular, both solar (i.e. photovoltaics) and wind energy are considered to be leading technologies with respect to electrical power generation. The study of photovoltaics (PV) has been carried out since the 1980s’ and is currently the most significant renewable energy resources available. According to the Renewable Energy Policy Network for the 21st Century (REN21), there has been a strong growth in the use of PV of 55 % and the worldwide solar PV electric capacity is expected to increase from 1,000 MW in 2000 to 140,000 MW by 2030 [5]. Moreover, it is forecast by the European Renewable Energy Council that this renewable electric energy could become sufficient to cover the base load and half of the global electricity energy demand by 2040 [6]. Generally in the PV industry, crystalline silicon has generally occupied about 95 % of the market share of materials, while only 5 % of all solar cells use amorphous silicon [7]. However, in order to improve the cost efficiency of solar cells by using less material, the thin-film PV module with amorphous silicon has become an active research and development (R&D) area [8]. In particular, solar cells that use amorphous silicon have the advantage of being able to generate a higher energy output under high temperatures than crystalline silicon solar cells, which are less affected by the temperature increase with respect to performance of electricity output than are the crystalline silicon solar cells. Moreover, installed at the rooftop and on the exterior wall of the building, a thin-film solar cell can be conveniently used as a facade that generates power for the entire building. This system is known as a building integrated photovoltaic system (BIPV). The thin-film solar cell can also provide the advantage of heat insulation and shading when incorporated into a harmonious building design. Therefore, the thin-film solar cell is expected to be a very bright prospect as a new engine for economical growth in the near future. Currently in Korea, many researchers are conducting

Inorganic semiconductor compounds, e.g., CIGS and CZTS, are promising materials for thin film solar cells because of their high light absorption coefficient and stability. Research on thin film solar cells using this compound has made remarkable progress in the last two decades. Vacuum-based processes, e.g., co-evaporation and sputtering, are well established to obtain high-efficiency CIGS and/or CZTS thin film solar cells with over 20% of power conversion. However, because the vacuum-based processes need high cost equipment, they pose technological barriers to producing low-cost and large area photovoltaic cells. Recently, non-vacuum based processes, for example the solution/nanoparticle precursor process, the electrodeposition method, or the polymer-capped precursors process, have been intensively studied to reduce capital expenditure. Lately, over 17% of energy conversion efficiency has been reported by solution precursors methods in CIGS solar cells. This article reviews the status of non-vacuum techniques that are used to fabricate CIGS and CZTS thin films solar cells.

Sputtered transparent electrodes for optoelectronic devices: Induced damage and mitigation strategies

Nontoxic and earth-abundant Cu2ZnSnS4 (CZTS) thin film solar cells: A review on high throughput processed methods

Thin film solar cells offer several benefits over conventional first-generation technologies including lighter weight, flexibility, and a wider range of optoelectronic tunability. Their environmental impact however needs to be investigated comprehensively to provide a clear comparison point with the first generation photovoltaics currently dominating the market. The main objective of this review is to evaluate current Life Cycle Assessment (LCA) studies conducted on thin film solar cells, highlighting the key parameters considered including life cycle stages, impact categories, and geographical locations. This included both commercially available thin film solar cells (a-Si, CIGS, CIS, CdTe, GaAs and GaAs tandem) as well as emerging (PSC, PSC tandem, DSSC, OPV, CZTS, QD) ones. A critical assessment of the results of 58 LCA studies was conducted and compared with traditional silicon based solar cells. Results indicate that emerging thin film solar cells hold great promise, as they tend to perform better than commercially available ones in the specified indicators, especially for CZTS and OPV. The assessment demonstrated that overall thin film solar cells had less energy requirement and better environmental performance than conventional crystalline silicon solar cell systems. However, due to their lower efficiencies their energy payback time was higher. This review provides a benchmark for the environmental LCA of different thin film solar cell technologies in order to highlight the relevance of these devices for sustainable energy generation and to give manufacturers and LCA experts information and a basis for future evaluation of solar cells.

In 1988, K. Ito and T. Nakazawa of Shinshu University succeeded in fabrication of Cu 2 ZnSnS 4 (CZTS) thin films by an atom beam sputtering method and confirmed that CZTS has suitable optical properties for thin film solar cells. In 1995, we began to develop the novel thin film solar cells using CZTS as an absorber to be able to use in the after next generation. The conversion efficiency of CZTS thin film solar cells reported for the first time in 1996 was only 0.66% and it have been improved to 6.77% in these twelve years at our laboratory. Quite recently, IBM using CZTSSe that contain Se to some extent achieved the conversion efficiency of over 10%. Because the potential of CZTS-based thin film solar cells seems to be quite high, we will be able to overcome the resource problem of rare-metal in the near future. In this talk we will survey our previous works and show the recent results concerning with this promising solar cells.

Characterization of lattice parameters gradient of Cu(In1-xGax)Se2 absorbing layer in thin-film solar cell by glancing incidence X-ray diffraction technique

Despite their maturity and market dominance, crystalline silicon (c-Si) solar cells and modules continue to develop rapidly, with increasing efficiencies and reducing cost ($/W). This contribution describes recent progress at SERIS with industrially relevant crystalline silicon solar cells and modules, covering both p-type and n-type cells. Since the costs of the solar cells and modules as a proportion of the costs of complete PV systems continue to fall, a premium is placed on cell efficiency as this reduces the balance of system (BOS) cost (in $/W) of PV systems. Thus, cost-effective monocrystalline high-efficiency silicon solar cells such as SERIS’ 23.5% efficient passivated-contact technology (“monoPolyTM”) have enormous market potential. Good progress is also being made in the SERIS laboratory with small-area perovskite/silicon tandem solar cells, giving efficiencies of over 25% in 4-terminal configuration. Keywords: Solar energy, photovoltaic devices, crystalline silicon solar cells, PERC solar cell, monoPolyTM solar cell, passivated contacts, perovskite solar cells, perovskite/silicon tandem solar cells.

Top PV market solar cells 2016

Recent progress in perovskite solar cells

I Introduction 1. Introduction to thin-film photovoltaics II Device characterization 2. Fundamental electrical characterization of thin-film solar cells 3. Electroluminescence analysis of thin-film solar modules 4. Capacitance spectroscopy of thin-film solar cells III Materials characterization 5. Characterizing the light trapping properties of textured surfaces with scanning near-field optical microscopy 6. Ellipsometry 7. Photoluminescence analysis of Si and chalcopyrite-type thin films for solar cells 8. Steady state photocarrier grating method 9. Time-of-flight analysis 10. Electron Spin Resonance on Si thin films for solar cells 11. Scanning probe microscopy on thin films for solar cells 12. Electron microscopy on thin films for solar cells 13. X-ray and neutron diffraction of materials for thin film solar cells 14. Raman Spectroscopy on thin films for solar cells 15. Soft x-ray and electron spectroscopy: a unique tool chest to characterize the chemical and electronic properties of surfaces and interfaces 16. Elemental distribution profiling of thin films for solar cells 17. Hydrogen effusion experiments IV Materials and device modelling 18. Ab-initio modelling of semiconductors 19. One-dimensional electro-optical simulations of thin film solar cells 20. Two-dimensional electrical simulations of thin film solar cells

One major factor affecting the performance of the kesterite \(\hbox {Cu}_{2} \hbox {ZnSnS}_{4}\) (CZTS) thin film solar cell is its low open circuit voltage (\({V}_\mathrm{oc}\)). In solar cells, transparent conducting oxides are components which act as electrode elements and their work functions control the open circuit voltage of the device. In this work, numerical modeling and simulation has been used to study the effect of various TCOs fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO) and indium tin oxide (ITO), on the performance characteristics of CZTS thin film solar cell. The usage of ITO gave the best performing device with a conversion efficiency of 9.98%, followed by AZO with 8.41% and FTO with 5.91%. Further optimization of some of the parameters of AZO and FTO shows that they are good alternative to the very expensive ITO. The effect of the variation in operating temperature indicates that AZO and FTO have better thermal stability. In addition, reduction in device thickness, application of FTO/AZO double layer and the filtering of the illumination within the visible spectrum enhanced the overall device performance which yielded an efficiency of 14.46%.

The semiconducting thin film solar cell based on Cu2ZnSnS4 (CZTS) materials is considered as a promising candidate for very large-scale application due to high absorption coefficient and low cost. In this study, the performances of n-ZnO/n-CdS/p-CZTS solar cells were numerically simulated using the AFORS-HET software. The influences of double-graded bandgap and thickness of CZTS layer on the performances of the solar cell were investigated. The calculated results show that double-graded bandgap structure can greatly optimize the conversion efficiency of CZTS thin film solar cell. The optimal dual gradient structure is 1.4 eV-1.3 eV-1.5 eV, the optimal thickness ratio is 11:1, and the conversion efficiency could be 26.63%. The results of this study can serve as a guide in fabricating CZTS solar cell.

Improving the silicon layer’s optical absorption is a key research point for crystalline silicon based thin film solar cells. Light trapping is a method widely adopted to achieve this research purpose. In this paper, we propose low loss interface photonic crystals layer (IPC), which is sandwiched between the crystalline silicon layer and the cover layer. The low loss interface photonic crystals layer could boost the light trapping efficiency significantly. The mechanism is that the smaller refraction index difference between silicon layer and the low loss interface photonic crystals layer could reduce the light’s interface reflection. Taking advantage of the coupling calculation by optical and electrical simulations, solar cell’s absorption efficiency and electrical performance parameters are obtained. Compared with optimized reference group, the maximum output power of the proposed solar cell could be improved by 6.44%. The result indicates that the proposed low loss interface photonic crystals layer is applicable for light’s trapping in crystalline silicon thin film solar cells.