Cu2Se is a promising"phonon liquid-electron crystal"thermoelectric material with excellent thermoelectric performance.In this work,Cd-doped Cu2-xSeCdx(x=0,0.0075,0.01,and 0.02)samples were prepared using NaC...Cu2Se is a promising"phonon liquid-electron crystal"thermoelectric material with excellent thermoelectric performance.In this work,Cd-doped Cu2-xSeCdx(x=0,0.0075,0.01,and 0.02)samples were prepared using NaCl flux method.The solubility of Cd in Cu2Se at room temperature was less than 6%,and a second phase of CdSe was found in the samples with large initial Cd content(x=0.01 and 0.02).Field-emission scanning electron microscopic image showed that the arranged lamellae formed a large-scale layered structure with an average thickness of approximately 100 nm.Transmission electron microscopy demonstrated that doping of Cd atoms did not destroy the crystal integrity of Cu2Se.A small amount of Cd in Cu2Se could reduce the electrical and thermal conductivities of the material,thus significantly enhancing its thermoelectric performance.With the increase in Cd content in the sample,the carrier concentration decreased and the mobility increased gradually.Thermogravimetric differential thermal analysis showed that no weight loss occurred below the melting point.Excessive Cd doping led to the emergence of the second phase of CdSe in the sample,thus significantly increasing the thermal conductivity of the material.A maximum ZT value of 1.67 at 700 K was obtained in the Cu1.9925SeCd0.0075 sample.展开更多
Deposition and structural characteristics of cadmium sulfide (CdS) thin films by chemical bath deposition (CBD) technique from a bath containing thiourea,cadmium acetate,ammonium acetate and ammonia in an aqueous solu...Deposition and structural characteristics of cadmium sulfide (CdS) thin films by chemical bath deposition (CBD) technique from a bath containing thiourea,cadmium acetate,ammonium acetate and ammonia in an aqueous solution are reported.Researches are made on the influence of the fundamental parameters including pH,temperature,and concentrations of the solution involved in the chemical bath deposition of CdS and titration or dumping of the thiourea solution on the structure characteristic of CdS thin films.The pH of the solution plays a vital role on the characteristic of the CdS thin films.The XRD patterns show that the change in the pH of the solution results in the change in crystal phase from predominant hexagonal phase to predominant cubic phase.The CdS thin films with the two different crystal phases have different influences on CIGS thin film solar cells.The crystal mismatch and the interface state density of the c-CdS(cubic phase CdS) and CIGS are about 1 419% and 8 507×10 12cm -2 respectively,and those of the h-CdS(hexagonal phase CdS) and CIGS are about 32 297% and 2 792×10 12cm -2 respectively.It is necessary for high efficiency CIGS thin film solar cells to deposit the cubic phase CdS thin films.展开更多
温度特性是太阳电池的一个重要特征,本文研究了Cu(In,Ga)Se_2(CIGS)薄膜太阳电池的输出特性随温度变化(120~260 K))的规律。发现,随着温度升高,开路电压Voc明显降低,温度系数为-1.08m V/K,短路电流Isc小幅升高,温度系数为0.01401 m A/K...温度特性是太阳电池的一个重要特征,本文研究了Cu(In,Ga)Se_2(CIGS)薄膜太阳电池的输出特性随温度变化(120~260 K))的规律。发现,随着温度升高,开路电压Voc明显降低,温度系数为-1.08m V/K,短路电流Isc小幅升高,温度系数为0.01401 m A/K。这是因为:随着温度上升,禁带宽度下降,暗电流增加,造成开路电压的降低;更多的光生载流子被激发,串联电阻有所下降,使得短路电流增加。两者共同作用,电池效率有所下降。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61864012 and 21701140)the Program for Innovative Research Team(in Science and Technology)in University of Yunnan Province,China.
文摘Cu2Se is a promising"phonon liquid-electron crystal"thermoelectric material with excellent thermoelectric performance.In this work,Cd-doped Cu2-xSeCdx(x=0,0.0075,0.01,and 0.02)samples were prepared using NaCl flux method.The solubility of Cd in Cu2Se at room temperature was less than 6%,and a second phase of CdSe was found in the samples with large initial Cd content(x=0.01 and 0.02).Field-emission scanning electron microscopic image showed that the arranged lamellae formed a large-scale layered structure with an average thickness of approximately 100 nm.Transmission electron microscopy demonstrated that doping of Cd atoms did not destroy the crystal integrity of Cu2Se.A small amount of Cd in Cu2Se could reduce the electrical and thermal conductivities of the material,thus significantly enhancing its thermoelectric performance.With the increase in Cd content in the sample,the carrier concentration decreased and the mobility increased gradually.Thermogravimetric differential thermal analysis showed that no weight loss occurred below the melting point.Excessive Cd doping led to the emergence of the second phase of CdSe in the sample,thus significantly increasing the thermal conductivity of the material.A maximum ZT value of 1.67 at 700 K was obtained in the Cu1.9925SeCd0.0075 sample.
文摘Deposition and structural characteristics of cadmium sulfide (CdS) thin films by chemical bath deposition (CBD) technique from a bath containing thiourea,cadmium acetate,ammonium acetate and ammonia in an aqueous solution are reported.Researches are made on the influence of the fundamental parameters including pH,temperature,and concentrations of the solution involved in the chemical bath deposition of CdS and titration or dumping of the thiourea solution on the structure characteristic of CdS thin films.The pH of the solution plays a vital role on the characteristic of the CdS thin films.The XRD patterns show that the change in the pH of the solution results in the change in crystal phase from predominant hexagonal phase to predominant cubic phase.The CdS thin films with the two different crystal phases have different influences on CIGS thin film solar cells.The crystal mismatch and the interface state density of the c-CdS(cubic phase CdS) and CIGS are about 1 419% and 8 507×10 12cm -2 respectively,and those of the h-CdS(hexagonal phase CdS) and CIGS are about 32 297% and 2 792×10 12cm -2 respectively.It is necessary for high efficiency CIGS thin film solar cells to deposit the cubic phase CdS thin films.
文摘温度特性是太阳电池的一个重要特征,本文研究了Cu(In,Ga)Se_2(CIGS)薄膜太阳电池的输出特性随温度变化(120~260 K))的规律。发现,随着温度升高,开路电压Voc明显降低,温度系数为-1.08m V/K,短路电流Isc小幅升高,温度系数为0.01401 m A/K。这是因为:随着温度上升,禁带宽度下降,暗电流增加,造成开路电压的降低;更多的光生载流子被激发,串联电阻有所下降,使得短路电流增加。两者共同作用,电池效率有所下降。
