Effects of K ions doping on the structure, morphology and optical properties of Cu2FeSnS4 thin films prepared by blade-coating process

Quaternary chalcogenide Cu2FeSnS4 (CFTS) nanoparticles, as a kind of potential absorber layer material in thin film solar cells (TFSCs), were successfully synthesized by using a convenient solvothermal method. Alkali element K is incorporated into CFTS thin films in order to further improve the surface morphology and the optical properties of related films. X-ray diffraction (XRD), Raman spectroscopy and field emission scanning electron microscopy (FESEM) were used to characterize the phase purity, morphology and composition of CFTS particles and thin films. The results show that the particle elemental ratios of Cu/(Fe+Sn) and Fe/Sn are 1.2 and 0.9, respectively, which are close to the characteristics of stoichiometric CFTS. The band gaps of CFTS films before and after doping K ions are estimated to be 1.44 eV and 1.4 eV with an error of ±0.02 eV. This work has been supported by National Natural Science Foundation of China (No. 51674026), and the Fundamental Research Funds for the Central Universities in 2015 (No.FRF-BD-15-004A). E-mail:chywang@yeah.net      

基于Cu掺杂ZnInS和ZnCdS量子点的高显色性白光LED

利用胶体化学方法合成了发光波长可调的Cu掺杂量子点, 其波长范围可从绿光到深红光连续调节.通过将绿光ZnInS :Cu和红光ZnCdS :Cu量子点与蓝光GaN芯片相结合, 制备了高显色性的白光LED, 其流明效率为71 lm·W^-1, 色温为4 788 K, 显色指数高达94, CIE色坐标为(0.352 4, 0.365 1).通过测量Cu掺杂量子点的荧光衰减曲线, 发现不存在从绿光ZnInS :Cu到红光ZnCdS :Cu量子点的能量传递过程, 因为红光ZnCdS :Cu量子点在绿光波段没有吸收. 实验结果表明, Cu掺杂量子点有望应用于固态照明领域.     

Synthesis and characterization of Cu2ZnSnS4 from Cu2SnS3 and ZnS compounds

The Cu2ZnSnS4 (CZTS) powders are successfully synthesized by using ZnS and Cu2SnS3 as raw materials directly without any intermediate phase at 450 °C for 3 h in Ar atmosphere. The crystalline structure, morphology and optical properties of the CZTS powders are characterized by X-ray diffraction (XRD), Raman spectrum, field emission scanning electron microscopy (FESEM) and ultraviolet-visible (UV-vis) spectrophotometer, respectively. The results show that the band gap of the obtained CZTS is 1.53 eV. The CZTS film is fabricated by spin coating a mixture of CZTS powders and novolac resin with a weight percentage of 30%. The photoelectrical properties of such CZTS films are measured, and the results show an incident light density of 100 mW.cm-2 with the bias voltage of 0.40 V, and the photocurrent density can approach 9.80×10-5 A.cm2within 50 s, giving an on/off switching ratio of 1.64.     

Synthesis of CuInSe2 nanoparticles by phase transformation of In2Se3 via wet chemical process in low temperature

Chalcopyrite-type CulnSe2 nanoparticles are successfully prepared by using In2Se3 nanoparticles as a precursor reacted with copper chloride （CuCl） solution via a phase transformation process in low temperature. The reaction time is a key parameter. After the reaction time increasing from 0.5 h to 8 h, In2Se3 and CuCl react with each other gradually via phase transformation into CuInSe2 without any intermediate phase. The crystalline structure and morphology of the CuInSe2 nanoparticles are characterized by X-ray diffraction （XRD） and field emission scanning electron microscopy （FESEM）. The diameter of CuInSe2 nanoparticles with good dispersibility ranges from 10 nm to 20 nm. The band gap of the CulnSe2 nanoparticles is 1.04 eV calculated from the ultraviolet-visible （UV-VIS） spectrum.     

Preparation and characteristics of Nb-doped indium tin oxide thin films by RF magnetron sputtering

Niobium-doped indium tin oxide(ITO:Nb)thin films are fabricated on glass substrates by radio frequency(RF)magnetron sputtering at different temperatures.Structural,electrical and optical properties of the films are investigated using X-ray diffraction(XRD),atomic force microscopy(AFM),ultraviolet-visible(UV-VIS)spectroscopy and electrical measurements.XRD patterns show that the preferential orientation of polycrystalline structure changes from(400)to(222)crystal plane,and the crystallite size increases with the increase of substrate temperature.AFM analyses reveal that the film is very smooth at low temperature.The root mean square(RMS)roughness and the average roughness are 2.16 nm and 1.64 nm,respectively.The obtained lowest resistivity of the films is 1.2×10-4?.cm,and the resistivity decreases with the increase of substrate temperature.The highest Hall mobility and carrier concentration are 16.5 cm2/V.s and 1.88×1021 cm-3,respectively.Band gap energy of the films depends on substrate temperature,which is varied from 3.49 eV to 3.63 eV.     

Study on the structural, electrical and optical properties of Al-F co-doped ZnO thin films prepared by RF magnetron sputtering

Al and F co-doped ZnO(ZnO:(Al,F)) thin films on glass substrates are prepared by the RF magnetron sputtering with different F doping contents.The structural,electrical and optical properties of the deposited films are sensitive to the F doping content.The X-ray analysis shows that the films are c-axis orientated along the(002) plane with the grain size ranging from 9 nm to 13 nm.Micrographs obtained by the scanning electron microscope(SEM) show a uniform surface.The best films obtained have a resistivity of 2.16×10-3Ω·cm,while the high optical transmission is 92.0% at the F content of 2.46 wt.%.     

Effect of thickness on optoelectrical properties of Nb-doped indium tin oxide thin films deposited by RF magnetron sputtering

Niobium-doped indium tin oxide （ITO:Nb） thin films are prepared on glass substrates with various film thicknesses by radio frequency （RF） magnetron sputtering from one piece of ceramic target material. The effects of thickness （60-360 nm） on the structural, electrical and optical properties of ITO: Nb films are investigated by means of X-ray diffraction （XRD）, ultraviolet （UV）-visible spectroscopy, and electrical measurements. XRD patterns show the highly oriented （400） direction. The lowest resistivity of the films without any heat treatment is 3.1×10^-4 Ω·cm^-1, and the resistivity decreases with the increase of substrate temperature. The highest Hall mobility and carrier concentration are 17.6 N·S and 1.36×10²¹ cm^-3, respectively. Band gap energy of the films depends on substrate temperature, which varies from 3.48 eV to 3.62 eV.     

Effects of parameters on the performance of amorphous IGZO thin films prepared by RF magnetron sputtering

Amorphous indium-gallium-zinc oxide （IGZO） transparent conductive thin films are prepared on glass substrates by radio frequency （RF） magnetron sputtering. The effects of seven factors, which are substrate temperature, sputtering atmosphere, working pressure, sputtering power, annealing temperature, negative bias voltage and sputtering time, on Hall mobility, transmittance and surface roughness are studied through orthogonal experiments. The results show that the effects of working pressure, substrate temperature and sputtering atmosphere on performance of films are the most prominent. According to the experimental results and discussion, relatively reasonable process parameters are obtained, which are working pressure of 0.35 Pa, substrate temperature of 200 ℃, sputtering atmosphere of Ar, sputtering power of 125 W, sputtering time of 30 min, negative bias voltage of 0 V and annealing temperature of 300 ℃.     

Synthesis and opto-electrical properties of Cu2NiSnS4 nanoparticles using a facile solid-phase process at low temperature

Cu2NiSnS4 nanoparticles were prepared for the first time using a facile solid-phase process at a temperature of 180 °C. The crystalline structure, morphology and optical properties of the Cu2NiSnS4 nanoparticles were characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM) and ultraviolet-visible (UV-vis) spectrophotometer. The band gap and conversion efficiency of Cu2NiSnS4 nanoparticles were studied at various temperature. The results showed that the Cu2NiSnS4 nanoparticles exhibited an optimum band gap of 1.58 eV and a conversion efficiency of 0.64% at 180 °C, indicating that it maybe be useful in low-cost thin film solar cells.     

(Al,Zr)共掺杂ZnO透明导电薄膜的结构以及光电性能研究

用射频磁控溅射法在玻璃衬底上氩气气氛中制备出(Al,Zr)共掺杂的ZnO透明导电薄膜,研究了不同Zr掺杂浓度和薄膜厚度ZnO薄膜的结构、电学和光学特性。结果表明,在最佳沉积条件下我们制备出了具有(002)单一择优取向的多晶六角纤锌矿结构,电阻率为2.2×10-2Ω.cm,且可见光段(320～800nm)平均透过率达到85%的ZnO透明导电薄膜。在150℃的条件下对(Al,Zr)共掺杂的ZnO薄膜进行1h的退火处理,薄膜电阻率降低至8.4×10-3Ω.cm。Zr杂质的掺入改善了薄膜的可见光透光性。