The effects of surface texturing on spherical silicon solar cells were investigated. Surface texturing for spherical Si solar cells was prepared by immersing p-type spherical Si crystals in KOH solution with stirring....The effects of surface texturing on spherical silicon solar cells were investigated. Surface texturing for spherical Si solar cells was prepared by immersing p-type spherical Si crystals in KOH solution with stirring. Two kinds of texture feature sizes (1 and 5 μm pyramids) were prepared by changing stirring speed. After fabrication through our baseline processes, these cells were evaluated by solar cell performance and external quantum efficiency. The cell with 1 and 5 μm pyramids shows the short circuit current density (Jsc) value of 31.9 and 33.2 mA·cm-2, which is 9% and 13% relative increase compared to the cell without texturing. Furthermore, the cell with 5 μm pyramids has a higher open-circuit voltage (0.589 V) than the cell with 1 μm pyramids (0.577 V). As a result, the conversion efficiency was improved from 11.4% for the cell without texturing to 12.1% for the cell with 5 μm pyramids.展开更多
A vacuum directional solidification with high temperature gradient was performed to prepare low cost solar-grade multicrystalline silicon （mc-Si） directly from metallurgical-grade mc-Si. The microstructure character...A vacuum directional solidification with high temperature gradient was performed to prepare low cost solar-grade multicrystalline silicon （mc-Si） directly from metallurgical-grade mc-Si. The microstructure characteristic, grain size, boundary, solid-liquid growth interface, and dislocation structure under different growth conditions were studied. The results show that directionally solidified multicrystalline silicon rods with high density and orientation can be obtained when the solidification rate is below 60 μm/s. The grain size gradually decreases with increasing the solidification rate. The control of obtaining planar solid-liquid interface at high temperature gradient is effective to produce well-aligned columnar grains along the solidification direction. The growth step and twin boundaries are preferred to form in the microstructure due to the faceted growth characteristic of mc-Si. The dislocation distribution is inhomogeneous within crystals and the dislocation density increases with the increase of solidification rate. Furthermore, the crystal growth behavior and dislocation formation mechanism of mc-Si were discussed.展开更多
Etching was performed on （100） silicon wafers using silicon-dissolved tetramethylammonium hydroxide （TMAH） solutions without the addition of surfactant. Experiments were carried out in different TMAH concentration...Etching was performed on （100） silicon wafers using silicon-dissolved tetramethylammonium hydroxide （TMAH） solutions without the addition of surfactant. Experiments were carried out in different TMAH concentrations at different temperatures for different etching times. The surface phenomena, etching rates, surface morphology and surface reflectance were analyzed. Experimental results show that the resulting surface covered with uniform pyramids can be realized with a small change in etching rates during the etching process. The etching mechanism is explained based on the experimental results and the theoretical considerations. It is suggested that all the components in the TMAH solutions play important roles in the etching process. Moreover, TMA^＋ ions may increase the wettability of the textured surface. A good textured surface can be obtained in conditions where the absorption of OH-/H2O is in equilibrium with that of TMA＋/SiO2（OH）2^-.展开更多
A stack of Al2O3/SiNx dual layer was applied for the back side surface passivation of p-type multi-crystalline silicon solar cells, with laser-opened line metal contacts, forming a local aluminum back surface field （...A stack of Al2O3/SiNx dual layer was applied for the back side surface passivation of p-type multi-crystalline silicon solar cells, with laser-opened line metal contacts, forming a local aluminum back surface field （local Al-BSF） structure. A slight amount of Al2O3, wrapping around to the front side of the wafer during the thermal atomic layer deposition process, was found to have a negative influence on cell performance. The different process flow was found to lead to a different cell performance, because of the Al2O3 wrapping around the front surface. The best cell performance, with an absolute efficiency gain of about 0.6% compared with the normal full Al-BSF structure solar cell, was achieved when the Al2O3 layer was deposited after the front surface of the wafer had been covered by a SiNx layer. We discuss the possible reasons for this phenomenon, and propose three explanations as the Ag paste, being hindered from firing through the front passivation layer, degraded the SiNx passivation effect and the Al2O3 induced an inversion effect on the front surface. Characterization methods like internal quantum efficiency and contact resistance scanning were used to assist our understanding of the underlying mechanisms.展开更多
Perovskite/silicon tandem solar cells(PVSK/Si TSCs)have emerged as a promising photovoltaic technology toward achieving a high power conversion efficiency(PCE)along with cost‐effective manufacturing.The PCE of PVSK/S...Perovskite/silicon tandem solar cells(PVSK/Si TSCs)have emerged as a promising photovoltaic technology toward achieving a high power conversion efficiency(PCE)along with cost‐effective manufacturing.The PCE of PVSK/Si TSCs has skyrocketed to a certified 33.9%,surpassing the theoretical limit of any single‐junction solar cell.This achievement is partially attributed to ad-vancements in surface textures for Si bottom cells.In this regard,we present an overview of the recent developments concerning surface textures of Si in monolithic PVSK/Si TSCs,including planar,pyramid texture,and nanotexture.Following,the prevailing perovskite deposition methods on these textures are thoroughly discussed,and the corresponding challenges are evaluated.Addi-tionally,we provide a summary of the advanced morphological,structural,optical,and electrical characterization techniques being utilized for theses textures.Finally,the prospects for further development of PVSK/Si TSCs are outlined,including designing novel textures with industrial compatibility,developing perovskite deposition methods with scalability,and exploring more pertinent characterization techniques for textured PVSK/Si TSCs.展开更多
Porous silicon （PS） layers were formed on textured crystalline silicon by electrochemical etching in HF- based electrolyte. Optical and electrical properties of the TMAH textured surfaces with PS formation are studi...Porous silicon （PS） layers were formed on textured crystalline silicon by electrochemical etching in HF- based electrolyte. Optical and electrical properties of the TMAH textured surfaces with PS formation are studied. Moreover, the influences of the initial structures and the anodizing time on the optical and electrical properties of the surfaces after PS formation are investigated. The results show that the TMAH textured surfaces with PS formation present a dramatic decrease in reflectance. The longer the anodizing time is, the lower the reflectance. Moreover, an initial surface with bigger pyramids achieved lower reflectance in a short wavelength range. A minimum reflectance of 3.86% at 460 nm is achieved for a short anodizing time of 2 min. Furthermore, the reflectance spectrum of the sample, which was etched in 3 vol.% TMAH for 25 min and then anodized for 20 min, is extremely flat and lies between 3.67% and 6.15% in the wavelength range from 400 to 1040 nm. In addition, for a short anodizing time, a slight increase in the effective carrier lifetime is observed. Our results indicate that PS layers formed on a TMAH textured surface for a short anodization treatment can be used as both broadband antireflection coatings and passivation layers for the application in solar cells.展开更多
基金This work was partly financially supported by NEDO as an Investigation for Innovative PV Technology Project and Nisshin Electric Co., Ltd.
文摘The effects of surface texturing on spherical silicon solar cells were investigated. Surface texturing for spherical Si solar cells was prepared by immersing p-type spherical Si crystals in KOH solution with stirring. Two kinds of texture feature sizes (1 and 5 μm pyramids) were prepared by changing stirring speed. After fabrication through our baseline processes, these cells were evaluated by solar cell performance and external quantum efficiency. The cell with 1 and 5 μm pyramids shows the short circuit current density (Jsc) value of 31.9 and 33.2 mA·cm-2, which is 9% and 13% relative increase compared to the cell without texturing. Furthermore, the cell with 5 μm pyramids has a higher open-circuit voltage (0.589 V) than the cell with 1 μm pyramids (0.577 V). As a result, the conversion efficiency was improved from 11.4% for the cell without texturing to 12.1% for the cell with 5 μm pyramids.
基金Projects (51002122, 51272211) supported by the National Natural Science Foundation of ChinaProject (2010ZF53064) supported by the Aeronautical Science Foundation of China+3 种基金Project (2012M51028) supported by the Postdoctoral Science Foundation of ChinaProject (2010JQ6005) supported by the Natural Science Foundation of Shaanxi Province, ChinaProject (76-QP-2011) supported by the Research Fund of State Key Laboratory of Solidification Processing in NWPU, ChinaProject (B08040) supported by the 111Project, China
文摘A vacuum directional solidification with high temperature gradient was performed to prepare low cost solar-grade multicrystalline silicon （mc-Si） directly from metallurgical-grade mc-Si. The microstructure characteristic, grain size, boundary, solid-liquid growth interface, and dislocation structure under different growth conditions were studied. The results show that directionally solidified multicrystalline silicon rods with high density and orientation can be obtained when the solidification rate is below 60 μm/s. The grain size gradually decreases with increasing the solidification rate. The control of obtaining planar solid-liquid interface at high temperature gradient is effective to produce well-aligned columnar grains along the solidification direction. The growth step and twin boundaries are preferred to form in the microstructure due to the faceted growth characteristic of mc-Si. The dislocation distribution is inhomogeneous within crystals and the dislocation density increases with the increase of solidification rate. Furthermore, the crystal growth behavior and dislocation formation mechanism of mc-Si were discussed.
基金Project supported by the National High Technology Research and Development Program of China(No.2007AA05Z437)
文摘Etching was performed on （100） silicon wafers using silicon-dissolved tetramethylammonium hydroxide （TMAH） solutions without the addition of surfactant. Experiments were carried out in different TMAH concentrations at different temperatures for different etching times. The surface phenomena, etching rates, surface morphology and surface reflectance were analyzed. Experimental results show that the resulting surface covered with uniform pyramids can be realized with a small change in etching rates during the etching process. The etching mechanism is explained based on the experimental results and the theoretical considerations. It is suggested that all the components in the TMAH solutions play important roles in the etching process. Moreover, TMA^＋ ions may increase the wettability of the textured surface. A good textured surface can be obtained in conditions where the absorption of OH-/H2O is in equilibrium with that of TMA＋/SiO2（OH）2^-.
文摘A stack of Al2O3/SiNx dual layer was applied for the back side surface passivation of p-type multi-crystalline silicon solar cells, with laser-opened line metal contacts, forming a local aluminum back surface field （local Al-BSF） structure. A slight amount of Al2O3, wrapping around to the front side of the wafer during the thermal atomic layer deposition process, was found to have a negative influence on cell performance. The different process flow was found to lead to a different cell performance, because of the Al2O3 wrapping around the front surface. The best cell performance, with an absolute efficiency gain of about 0.6% compared with the normal full Al-BSF structure solar cell, was achieved when the Al2O3 layer was deposited after the front surface of the wafer had been covered by a SiNx layer. We discuss the possible reasons for this phenomenon, and propose three explanations as the Ag paste, being hindered from firing through the front passivation layer, degraded the SiNx passivation effect and the Al2O3 induced an inversion effect on the front surface. Characterization methods like internal quantum efficiency and contact resistance scanning were used to assist our understanding of the underlying mechanisms.
基金Zhejiang Provincial Natural Science Foundation of China,Grant/Award Number:LY24F040003Key Research and Development Program of Zhejiang Province,Grant/Award Numbers:2022C01215,2024C01092+3 种基金Baima Lake Laboratory Joint Funds of the Zhejiang Provincial Natural Science Foundation of China,Grant/Award Number:LBMHD24E020002National Natural Science Foundation of China,Grant/Award Numbers:62204245,U23A200098China Postdoctoral Science Foundation,Grant/Award Number:2023M743620Key Research and Development Program of Ningbo,Grant/Award Number:2023Z151。
文摘Perovskite/silicon tandem solar cells(PVSK/Si TSCs)have emerged as a promising photovoltaic technology toward achieving a high power conversion efficiency(PCE)along with cost‐effective manufacturing.The PCE of PVSK/Si TSCs has skyrocketed to a certified 33.9%,surpassing the theoretical limit of any single‐junction solar cell.This achievement is partially attributed to ad-vancements in surface textures for Si bottom cells.In this regard,we present an overview of the recent developments concerning surface textures of Si in monolithic PVSK/Si TSCs,including planar,pyramid texture,and nanotexture.Following,the prevailing perovskite deposition methods on these textures are thoroughly discussed,and the corresponding challenges are evaluated.Addi-tionally,we provide a summary of the advanced morphological,structural,optical,and electrical characterization techniques being utilized for theses textures.Finally,the prospects for further development of PVSK/Si TSCs are outlined,including designing novel textures with industrial compatibility,developing perovskite deposition methods with scalability,and exploring more pertinent characterization techniques for textured PVSK/Si TSCs.
基金Project supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(No.KGCX2-YW-382).
文摘Porous silicon （PS） layers were formed on textured crystalline silicon by electrochemical etching in HF- based electrolyte. Optical and electrical properties of the TMAH textured surfaces with PS formation are studied. Moreover, the influences of the initial structures and the anodizing time on the optical and electrical properties of the surfaces after PS formation are investigated. The results show that the TMAH textured surfaces with PS formation present a dramatic decrease in reflectance. The longer the anodizing time is, the lower the reflectance. Moreover, an initial surface with bigger pyramids achieved lower reflectance in a short wavelength range. A minimum reflectance of 3.86% at 460 nm is achieved for a short anodizing time of 2 min. Furthermore, the reflectance spectrum of the sample, which was etched in 3 vol.% TMAH for 25 min and then anodized for 20 min, is extremely flat and lies between 3.67% and 6.15% in the wavelength range from 400 to 1040 nm. In addition, for a short anodizing time, a slight increase in the effective carrier lifetime is observed. Our results indicate that PS layers formed on a TMAH textured surface for a short anodization treatment can be used as both broadband antireflection coatings and passivation layers for the application in solar cells.
文摘在单晶硅太阳能电池的制备过程中,经常利用碱溶液对电池表面进行“织构”,以形成陷光,增强对光的吸收.在NaOH溶液中制备硅片时,由于各个晶面的腐蚀速率不同,在硅片表面会形成类“金字塔”形绒面.碱溶液浓度、添加剂用量、反应温度以及时间等都会影响到绒面的形成.文中通过正交试验方法,分析了各个因素对绒面形成的影响,得出了最佳的试验条件为:碱溶液浓度为2.5%;反应温度为95℃;添加剂用量为5%;腐蚀时间为30m in.
