The graded bandgap of kesterite based absorber layer is an important way to achieve high efficiency solar cells. Incorporation of Ag into CZTSSe thin films can adjust the bandgap and thus reduce the VOC-deficit and im...The graded bandgap of kesterite based absorber layer is an important way to achieve high efficiency solar cells. Incorporation of Ag into CZTSSe thin films can adjust the bandgap and thus reduce the VOC-deficit and improve the quality of crystallization. However, the distribution of Ag is difficult to control due to the quick diffusion of Ag under the high temperature. In this study, we achieve the front Ag-gradient in kesterite structured compound films by prealloying followed by selenization process at 550 °C. AgZn3,Ag3Sn, and Sn–Ag–Cu alloy phases were formed during prealloying stage at 250 °C. After prealloying process, Ag tends to distribute at the front surface of the ACZTSe thin films. Combining the results of experiment and SCAPS simulation, the significantly VOCimprovement of devices is ascribed to the formation of the front Ag-gradient bandgap structure in the absorber layer. This facile prealloying selenization process affords a feasible method to design the graded bandgap structure absorber layers, which will promote the fabrication of high efficient graded bandgap structure solar cells.展开更多
文章采用N,N-双(丙烯酰)胱胺(BACA)修饰银纳米线(AgNWs)作为多功能大分子交联剂和导电填料,以丙烯酸钠为离子型可聚合单体,重力场作用诱导多功能大分子交联剂组装形成质量浓度梯度,在催化剂和热引发条件下发生自由基聚合反应,制备基于...文章采用N,N-双(丙烯酰)胱胺(BACA)修饰银纳米线(AgNWs)作为多功能大分子交联剂和导电填料,以丙烯酸钠为离子型可聚合单体,重力场作用诱导多功能大分子交联剂组装形成质量浓度梯度,在催化剂和热引发条件下发生自由基聚合反应,制备基于质量浓度梯度的高度各向异性纳米复合水凝胶。通过扫描电子显微镜(scanning electron microscope,SEM)、透射电子显微镜(transmission electron microscope,TEM)、万能材料测试仪、电化学工作站、红外热像仪等对所制备的纳米复合水凝胶进行表征,结果表明,该纳米复合水凝胶网络密度自上而下逐级提高,表现出高度各向异性的机械、电学、光热等行为。通过对其相关性能的检测,结果表明,该纳米复合水凝胶可以快速地在水条件和近红外辐照下发生不对称形状变化,在柔性智能驱动领域有着广阔的应用前景。展开更多
Sn-Bi-X solders are widely used in electronic packaging industry.However,thermomigration(TM)behaviors of Sn-BiX solder joints and the orientations change of Bi grains under the temperature gradient are rarely reported...Sn-Bi-X solders are widely used in electronic packaging industry.However,thermomigration(TM)behaviors of Sn-BiX solder joints and the orientations change of Bi grains under the temperature gradient are rarely reported.In this study,Sn-Bi57-Ag0.7/Cu solder joints were used to conduct a TM test under a temperature gradient of 625℃/cm for 400 h,and an isothermal aging test at 85℃was also conducted for comparison.The microstructural evolution of Sn-Bi-X solder joints after reflow,TM and isothermal aging were analyzed by scanning electron microscopy(SEM),transmission electron microscopy(TEM)and electron probe microanalysis(EPMA).The results indicated that the Sn/Bi areal ratio after TM did not change significantly whether at the hot end(from 46.78%/52.12%to 50.90%/48.78%)or at the cold end(from 50.25%/49.64%to 48.71%/51.16%)compared with that of as-reflowed samples due to the insufficient thermal energy.The thickness of intermetallic compound(IMC)after TM at hot end(2.49μm)was very close to that of the IMC at cold end(2.52μm),which was also close to that of the aged samples.In addition,the preferred orientations of Sn and Bi grains in different Sn–Bi–Ag solder joints resulting from different conditions(reflow,TM and isothermal aging)were characterized by electron backscatter diffraction(EBSD).The obtained results demonstrated that both Sn and Bi grains had no preferred orientation whether after reflowor isothermal aging,while the orientation of Bi grains of the sample after TM changed from random direction to c-axis([0001]direction)parallel to the heat flow.Ag 3 Sn could hinder the change of orientation of Bi grains under the temperature gradient,and the corresponding mechanism was also systematically illuminated.This study firstly revealed the orientation change of Bi grains under the temperature gradient,which would have a profound guiding significance for enhancing the reliabilities of Sn–Bi–Ag solder joints.展开更多
基金supported by the National Natural Science Foundation of China(51572132,61674082,61774089)Tianjin Natural Science Foundation of Key Project(16JCZDJC30700,18JCZDJC31200)+1 种基金YangFan Innovative and Entrepreneurial Research Team Project(2014YT02N037)111 Project(B16027)
文摘The graded bandgap of kesterite based absorber layer is an important way to achieve high efficiency solar cells. Incorporation of Ag into CZTSSe thin films can adjust the bandgap and thus reduce the VOC-deficit and improve the quality of crystallization. However, the distribution of Ag is difficult to control due to the quick diffusion of Ag under the high temperature. In this study, we achieve the front Ag-gradient in kesterite structured compound films by prealloying followed by selenization process at 550 °C. AgZn3,Ag3Sn, and Sn–Ag–Cu alloy phases were formed during prealloying stage at 250 °C. After prealloying process, Ag tends to distribute at the front surface of the ACZTSe thin films. Combining the results of experiment and SCAPS simulation, the significantly VOCimprovement of devices is ascribed to the formation of the front Ag-gradient bandgap structure in the absorber layer. This facile prealloying selenization process affords a feasible method to design the graded bandgap structure absorber layers, which will promote the fabrication of high efficient graded bandgap structure solar cells.
文摘文章采用N,N-双(丙烯酰)胱胺(BACA)修饰银纳米线(AgNWs)作为多功能大分子交联剂和导电填料,以丙烯酸钠为离子型可聚合单体,重力场作用诱导多功能大分子交联剂组装形成质量浓度梯度,在催化剂和热引发条件下发生自由基聚合反应,制备基于质量浓度梯度的高度各向异性纳米复合水凝胶。通过扫描电子显微镜(scanning electron microscope,SEM)、透射电子显微镜(transmission electron microscope,TEM)、万能材料测试仪、电化学工作站、红外热像仪等对所制备的纳米复合水凝胶进行表征,结果表明,该纳米复合水凝胶网络密度自上而下逐级提高,表现出高度各向异性的机械、电学、光热等行为。通过对其相关性能的检测,结果表明,该纳米复合水凝胶可以快速地在水条件和近红外辐照下发生不对称形状变化,在柔性智能驱动领域有着广阔的应用前景。
基金partially supported by the National Key R&D Program of China(No.2017YFB0305700)。
文摘Sn-Bi-X solders are widely used in electronic packaging industry.However,thermomigration(TM)behaviors of Sn-BiX solder joints and the orientations change of Bi grains under the temperature gradient are rarely reported.In this study,Sn-Bi57-Ag0.7/Cu solder joints were used to conduct a TM test under a temperature gradient of 625℃/cm for 400 h,and an isothermal aging test at 85℃was also conducted for comparison.The microstructural evolution of Sn-Bi-X solder joints after reflow,TM and isothermal aging were analyzed by scanning electron microscopy(SEM),transmission electron microscopy(TEM)and electron probe microanalysis(EPMA).The results indicated that the Sn/Bi areal ratio after TM did not change significantly whether at the hot end(from 46.78%/52.12%to 50.90%/48.78%)or at the cold end(from 50.25%/49.64%to 48.71%/51.16%)compared with that of as-reflowed samples due to the insufficient thermal energy.The thickness of intermetallic compound(IMC)after TM at hot end(2.49μm)was very close to that of the IMC at cold end(2.52μm),which was also close to that of the aged samples.In addition,the preferred orientations of Sn and Bi grains in different Sn–Bi–Ag solder joints resulting from different conditions(reflow,TM and isothermal aging)were characterized by electron backscatter diffraction(EBSD).The obtained results demonstrated that both Sn and Bi grains had no preferred orientation whether after reflowor isothermal aging,while the orientation of Bi grains of the sample after TM changed from random direction to c-axis([0001]direction)parallel to the heat flow.Ag 3 Sn could hinder the change of orientation of Bi grains under the temperature gradient,and the corresponding mechanism was also systematically illuminated.This study firstly revealed the orientation change of Bi grains under the temperature gradient,which would have a profound guiding significance for enhancing the reliabilities of Sn–Bi–Ag solder joints.
