In this work, we have modeled and simulated the electrical performance of CIGS thin-film solar cell using one-dimensional simulation software (SCAPS-1D). Starting from a baseline model that reproduced the experimental...In this work, we have modeled and simulated the electrical performance of CIGS thin-film solar cell using one-dimensional simulation software (SCAPS-1D). Starting from a baseline model that reproduced the experimental results, the properties of the absorber layer and the CIGS/Mo interface have been explored, and the requirements for high-efficiency CIGS solar cell were proposed. Simulation results show that the band-gap, acceptor density, defect density are crucial parameters that affect the performance of the solar cell. The best conversion efficiency is obtained when the absorber band-gap is around 1.2 eV, the acceptor density at 10<sup>16</sup> cm<sup><span style="white-space:nowrap;">−</span>3</sup> and the defect density less than 10<sup>14</sup> cm<sup><span style="white-space:nowrap;">−</span>3</sup>. In addition, CIGS/Mo interface has been investigated. It appears that a thin MoSe<sub>2</sub> layer reduces recombination at this interface. An improvement of 1.5 to 2.5 mA/cm<sup>2</sup> in the current density (<em>J<sub>sc</sub></em>) depending on the absorber thickness is obtained.展开更多
The development of cadmium-free CIGS solar cells with high conversion efficiency is crucial due to the toxicity of cadmium. Zinc-based buffer layers seem to be the most promising. In this paper, a numerical analysis u...The development of cadmium-free CIGS solar cells with high conversion efficiency is crucial due to the toxicity of cadmium. Zinc-based buffer layers seem to be the most promising. In this paper, a numerical analysis using SCAPS-1D software was used to explore the Zn(Mg,O) layer as an alternative to the toxic CdS layer. The effect of several properties such as thickness, doping, Mg concentration of the Zn(Mg,O) layer on the current-voltage parameters was explored and their optimal values were proposed. The simulation results reveal that the optimal value of the ZMO layer thickness is approximately 40 nm, the doping at 10<sup>17</sup> cm<sup>-3</sup> and an Mg composition between 0.15 and 0.2. In addition, the effect of Gallium (Ga) content in the absorber as well as the Zn(Mg,O)/CIGS interface properties on the solar cell’s performance was examined. The results show that contrary to the CdS buffer layer, the best electrical characteristics of the ZMO/CIGS heterojunction are obtained using a Ga-content equal to 0.4 and high interface defect density or unfavorable band alignment may be the causes of poor performances of Zn(Mg,O)/CIGS solar cells in the case of low and high Mg-contents.展开更多
The beneficial effect of the alkali metals such as Na and K on the Cu（In.Ga）Se2 （CIGS） and Cu2ZnSn（S,Se）4 （CZTSSe） solar cells has been extensively investigated in the past two decades, however, in most of the...The beneficial effect of the alkali metals such as Na and K on the Cu（In.Ga）Se2 （CIGS） and Cu2ZnSn（S,Se）4 （CZTSSe） solar cells has been extensively investigated in the past two decades, however, in most of the studies the alkali metals were treated as dopants. Several recent studies have showed that the alkali metals may not only act as dopants but also form secondary phases in the absorber layer or on the surfaces of the films. Using the first-principles calculations, we screened out the most probable secondary phases of Na and K in CIGS and CZTSSe, and studied their electronic structures and optical properties. We found that all these alkali chalcogenide compounds have larger band gaps and lower VBM levels than CIGS and CZTSSe, because the existence of strong p-d coupling in CIS and CZTS pushes the valence band maximum （VBM） level up and reduces the band-gaps, while there is no such p-d coupling in these alkali chalcogenides. This band alignment repels the photo-generated holes from the secondary phases and prevents the electron-hole recombination. Moreover, the study on the optical properties of the secondary phases showed that the absorption coefficients of these alkali chalcogenides are much lower than those of CIGS and CZTSSe in the energy range of 0-3.4eV, which means that the alkali chalcogenides may not influence the absorption of solar light. Since the alkali metal dopants can passivate the grain boundaries and increase the hole carrier concentration, and meanwhile their related secondary phases have innocuous effect on the optical absorption and band alignment, we can understand why the alkali metal dopants can improve the CIGS and CZTSSe solar cell performance.展开更多
In order to achieve low cost high efficiency thin film solar cells,a novel Semiconductor Photovoltaic (PV) active material CuIn 1-x Ga x Se 2 (CIGS) and thin film Electro Deposition (ED) technology is explored.Firstly...In order to achieve low cost high efficiency thin film solar cells,a novel Semiconductor Photovoltaic (PV) active material CuIn 1-x Ga x Se 2 (CIGS) and thin film Electro Deposition (ED) technology is explored.Firstly,the PV materials and technologies is investigated,then the detailed experimental processes of CIGS/Mo/glass structure by using the novel ED technology and the results are reported.These results shows that high quality CIGS polycrystalline thin films can be obtained by the ED method,in which the polycrystalline CIGS is definitely identified by the (112),(204,220) characteristic peaks of the tetragonal structure,the continuous CIGS thin film layers with particle average size of about 2μm of length and around 1 6μm of thickness.The thickness and solar grade quality of CIGS thin films can be produced with good repeatability.Discussion and analysis on the ED technique,CIGS energy band and sodium (Na) impurity properties,were also performed.The alloy CIGS exhibits not only increasing band gap with increasing x ,but also a change in material properties that is relevant to the device operation.The beneficial impurity Na originating from the low cost soda lime glass substrate becomes one prerequisite for high quality CIGS films.These novel material and technology are very useful for low cost high efficiency thin film solar cells and other devices.展开更多
文摘In this work, we have modeled and simulated the electrical performance of CIGS thin-film solar cell using one-dimensional simulation software (SCAPS-1D). Starting from a baseline model that reproduced the experimental results, the properties of the absorber layer and the CIGS/Mo interface have been explored, and the requirements for high-efficiency CIGS solar cell were proposed. Simulation results show that the band-gap, acceptor density, defect density are crucial parameters that affect the performance of the solar cell. The best conversion efficiency is obtained when the absorber band-gap is around 1.2 eV, the acceptor density at 10<sup>16</sup> cm<sup><span style="white-space:nowrap;">−</span>3</sup> and the defect density less than 10<sup>14</sup> cm<sup><span style="white-space:nowrap;">−</span>3</sup>. In addition, CIGS/Mo interface has been investigated. It appears that a thin MoSe<sub>2</sub> layer reduces recombination at this interface. An improvement of 1.5 to 2.5 mA/cm<sup>2</sup> in the current density (<em>J<sub>sc</sub></em>) depending on the absorber thickness is obtained.
文摘The development of cadmium-free CIGS solar cells with high conversion efficiency is crucial due to the toxicity of cadmium. Zinc-based buffer layers seem to be the most promising. In this paper, a numerical analysis using SCAPS-1D software was used to explore the Zn(Mg,O) layer as an alternative to the toxic CdS layer. The effect of several properties such as thickness, doping, Mg concentration of the Zn(Mg,O) layer on the current-voltage parameters was explored and their optimal values were proposed. The simulation results reveal that the optimal value of the ZMO layer thickness is approximately 40 nm, the doping at 10<sup>17</sup> cm<sup>-3</sup> and an Mg composition between 0.15 and 0.2. In addition, the effect of Gallium (Ga) content in the absorber as well as the Zn(Mg,O)/CIGS interface properties on the solar cell’s performance was examined. The results show that contrary to the CdS buffer layer, the best electrical characteristics of the ZMO/CIGS heterojunction are obtained using a Ga-content equal to 0.4 and high interface defect density or unfavorable band alignment may be the causes of poor performances of Zn(Mg,O)/CIGS solar cells in the case of low and high Mg-contents.
基金supported by the National Natural Science Foundation of China(NSFC)under grant nos.61574059 and 61722402the National Key Research and Development Program of China(2016YFB0700700)+1 种基金Shu-Guang program(15SG20)CC of ECNU
文摘The beneficial effect of the alkali metals such as Na and K on the Cu（In.Ga）Se2 （CIGS） and Cu2ZnSn（S,Se）4 （CZTSSe） solar cells has been extensively investigated in the past two decades, however, in most of the studies the alkali metals were treated as dopants. Several recent studies have showed that the alkali metals may not only act as dopants but also form secondary phases in the absorber layer or on the surfaces of the films. Using the first-principles calculations, we screened out the most probable secondary phases of Na and K in CIGS and CZTSSe, and studied their electronic structures and optical properties. We found that all these alkali chalcogenide compounds have larger band gaps and lower VBM levels than CIGS and CZTSSe, because the existence of strong p-d coupling in CIS and CZTS pushes the valence band maximum （VBM） level up and reduces the band-gaps, while there is no such p-d coupling in these alkali chalcogenides. This band alignment repels the photo-generated holes from the secondary phases and prevents the electron-hole recombination. Moreover, the study on the optical properties of the secondary phases showed that the absorption coefficients of these alkali chalcogenides are much lower than those of CIGS and CZTSSe in the energy range of 0-3.4eV, which means that the alkali chalcogenides may not influence the absorption of solar light. Since the alkali metal dopants can passivate the grain boundaries and increase the hole carrier concentration, and meanwhile their related secondary phases have innocuous effect on the optical absorption and band alignment, we can understand why the alkali metal dopants can improve the CIGS and CZTSSe solar cell performance.
基金Project Supported by the Innovation and Technology Fund ( ITF ) of The Government of The Hong Kong Special Administrative Region ( HK-SAR)China( Fund Grant Num ber:S/ P0 0 5 / 99)
文摘In order to achieve low cost high efficiency thin film solar cells,a novel Semiconductor Photovoltaic (PV) active material CuIn 1-x Ga x Se 2 (CIGS) and thin film Electro Deposition (ED) technology is explored.Firstly,the PV materials and technologies is investigated,then the detailed experimental processes of CIGS/Mo/glass structure by using the novel ED technology and the results are reported.These results shows that high quality CIGS polycrystalline thin films can be obtained by the ED method,in which the polycrystalline CIGS is definitely identified by the (112),(204,220) characteristic peaks of the tetragonal structure,the continuous CIGS thin film layers with particle average size of about 2μm of length and around 1 6μm of thickness.The thickness and solar grade quality of CIGS thin films can be produced with good repeatability.Discussion and analysis on the ED technique,CIGS energy band and sodium (Na) impurity properties,were also performed.The alloy CIGS exhibits not only increasing band gap with increasing x ,but also a change in material properties that is relevant to the device operation.The beneficial impurity Na originating from the low cost soda lime glass substrate becomes one prerequisite for high quality CIGS films.These novel material and technology are very useful for low cost high efficiency thin film solar cells and other devices.
