Gallium gradients in Cu(In,Ga)Se2 thin‐film solar cells

The gallium gradient in Cu(In,Ga)Se₂ (CIGS) layers, which forms during the two industrially relevant deposition routes, the sequential and co‐evaporation processes, plays a key role in the device performance of CIGS thin‐film modules. In this contribution, we present a comprehensive study on the formation, nature, and consequences of gallium gradients in CIGS solar cells. The formation of gallium gradients is analyzed in real time during a rapid selenization process by in situ X‐ray measurements. In addition, the gallium grading of a CIGS layer grown with an in‐line co‐evaporation process is analyzed by means of depth profiling with mass spectrometry. This gallium gradient of a real solar cell served as input data for device simulations. Depth‐dependent occurrence of lateral inhomogeneities on the µm scale in CIGS deposited by the co‐evaporation process was investigated by highly spatially resolved luminescence measurements on etched CIGS samples, which revealed a dependence of the optical bandgap, the quasi‐Fermi level splitting, transition levels, and the vertical gallium gradient. Transmission electron microscopy analyses of CIGS cross‐sections point to a difference in gallium content in the near surface region of neighboring grains. Migration barriers for a copper‐vacancy‐mediated indium and gallium diffusion in CuInSe₂ and CuGaSe₂ were calculated using density functional theory. The migration barrier for the In_Cu antisite in CuGaSe₂ is significantly lower compared with the Ga_Cu antisite in CuInSe₂, which is in accordance with the experimentally observed Ga gradients in CIGS layers grown by co‐evaporation and selenization processes. Copyright © 2014 John Wiley & Sons, Ltd.     

Electrodeposited Cu2ZnSnSe4 thin film solar cell with 7% power conversion efficiency

High performance Cu₂ZnSnSe₄ (CZTSe) photovoltaic materials were synthesized by electrodeposition of metal stack precursors followed by selenization. A champion solar cell with 7.0% efficiency is demonstrated. This is the highest efficiency among all of the CZTSe solar cells prepared from electrodeposited metallic precursors reported to‐date. Device parameters are discussed from the perspective of material microstructure and composition in order to improve performance. In addition, a high performance electrodeposited CZTS (S only) solar cell was demonstrated and its device characteristics were compared against the CZTSe (Se only) cell. Using secondary ion mass spectrometry for the analysis of the chemical composition of the absorber layer, a higher concentration of oxygen in the electrodeposited absorber is thought to be the root cause of the lower performance of the electrodeposited CZTS or CZTSe solar cells with respect to a solar cell fabricated by evaporation. The grain boundary areas of Sn‐rich composition are thought to be responsible for the lower shunt resistance commonly observed in CZTSe devices. We measured the longest minority carrier lifetime of 18 ns among all reported kesterite devices. This work builds a good baseline for obtaining higher efficiency earth‐abundant solar cells, while it highlights electrodepositon as a low cost and feasible method for earth‐abundant thin film solar cell fabrication. Copyright © 2013 John Wiley & Sons, Ltd.     

硒化二氢杨梅素的制备及抗肿瘤活性

以DMY为基底物、Na2SeO3为硒化剂制备硒化DMY。采用UV、FTIR、NMR、XRD、TG、原子荧光光度计表征其结构和性能，CCK-8法检测对HSC-3细胞增殖的影响，划痕实验研究对HSC-3细胞迁移的影响。结果表明，硒化DMY中仍存在黄酮基本母核、并新形成C-Se键，其中硒含量为6.54%±0.22%；DMY和硒化DMY均对HSC-3细胞的增殖和迁移有良好的抑制作用、抑制效果与浓度呈正相关，且DMY和硒化DMY对HSC-3细胞的半数抑制浓度（IC50）分别为25.27 μg/mL、21.27 μg/mL，DMY的硒化有效提高了对HSC-3细胞增殖和迁移的抑制能力。     

PdSe2半导体薄膜的真空硒化法制备研究

PdSe₂薄膜主要通过机械剥离法和气相沉积法制得, 本研究采用一种简单有效的可在SiO₂/Si衬底上制备PdSe₂薄膜的方法。通过高真空磁控溅射技术在SiO₂/Si衬底上沉积一层Pd金属薄膜, 将Pd金属薄膜与Se粉封在高真空的石英管中并在一定的温度下进行硒化, 获得PdSe₂薄膜。根据截面高分辨透射电镜(HRTEM)照片可知PdSe₂薄膜的平均厚度约为30 nm。进一步研究硒化温度对PdSe₂薄膜电输运性能的影响, 当硒化温度为300 ℃时, 所制得的PdSe₂薄膜的体空穴浓度约为1×10¹⁸ cm^-3, 具有最大的室温迁移率和室温磁阻, 分别为48.5 cm²·V^-1·s^-1和12%(B=9 T)。值得注意的是, 本实验中通过真空硒化法获得的薄膜空穴迁移率大于通过机械剥离法制得的p型PdSe₂薄膜。随着硒化温度从300 ℃逐渐升高, 由于Se元素容易挥发, Pd薄膜的硒化程度逐渐减小, 导致薄膜硒含量、迁移率和磁电阻降低。本研究表明：真空硒化法是一种简单有效地制备PdSe₂薄膜的方法, 在贵金属硫族化合物的大面积制备及多功能电子器件的设计中具有潜在的应用价值。     

硒化温度对SnSe2薄膜材料性能的影响

采用射频磁控溅射加硒化的两步法在超白玻璃衬底上生长SnSe₂薄膜,采用XRD、光学透过谱、Raman光谱、XPS和SEM等方法对薄膜进行性能表征。通过设置不同的硒化温度,研究不同硒化温度对所得薄膜相结构、物相与组分、表面形貌等性能的影响。结果表明:350℃,40min硒化所得薄膜为片状晶粒,光学带隙为1.46eV,相结构和均匀性等性能在该硒化条件下均为最佳。     

冬凌草硒多糖的制备、表征及抗氧化活性分析

本研究以济源冬凌草多糖为原料，选用化学合成方法对多糖进行结构修饰。采用UV、FT-IR、SEM、TGA、HPLC等方法对冬凌草多糖以及硒多糖结构特征进行了表征；通过DPPH（1,1-二苯基-2-三硝基苯肼）自由基法、羟自由基法等4种方法对其抗氧化活性进行了探究。结果：制备的硒多糖中硒质量分数为1.35 mg/g。硒化修饰后，冬凌草多糖的基本骨架得到保留，单糖种类未发生改变，但其分解温度降低、稳定性下降，多糖形貌也发生明显变化，球状与条状形貌增多，片状形貌减少。此外，在体外抗氧化性实验中，当硒多糖质量浓度为1.6mg/mL时，对DPPH自由基、ABTS自由基、羟自由基清除率分别为68.68%、86.69%、45.12%，均强于冬凌草多糖。     

金属预置层后硒化法制备CIGS薄膜的研究进展

系统综述了国内外采用金属预置层后硒化法制备Cu(In,Ga)Se2(CIGS)薄膜的研究进展,重点从预置层制备过程中靶材的选择、叠层方式以及后硒化过程中硒源种类和硒化方式的选择等几个方面对各种工艺的优点、存在的问题和可能的解决方案进行讨论,并对金属预置层后硒化法的发展前景和趋势进行了展望。     

Fabrication of Cu(In,Ga)Se2 thin films by sputtering from a single quaternary chalcogenide target

Single‐layered Cu‐In‐Ga‐Se precursors were fabricated by one‐step sputtering of a single quaternary Cu(In,Ga)Se₂ (CIGS) chalcogenide target at room temperature, followed by post selenization using Se vapor obtained from elemental Se pellets. The morphological and structural properties of both as‐deposited and selenized films were characterized by X‐ray diffraction (XRD), Raman spectroscope and scanning electron microscope (SEM). The precursor films exhibited a chalcopyrite structure with a preferential orientation in the (112) direction. The post‐selenization process at high‐temperature significantly improved the quality of the chalcopyrite CIGS. The CIGS layers after post‐selenization were used to fabricate solar cells. The solar cell had an open‐circuit voltage Voc of 0.422 V, a short‐circuit current density J = 24.75 mA, a fill factor of 53.29%, and an efficiency of 7.95%. Copyright © 2010 John Wiley & Sons, Ltd.     

CuIn1−xGaxSe2‐based thin‐film solar cells by the selenization of sequentially evaporated metallic layers

Polycrystalline CuIn_1−xGa_xSe₂ (CIGS) thin films were deposited by the non‐vacuum, near‐atmospheric‐pressure selenization of stacked metallic precursor layers. A study was carried out to investigate the influence of significant factors of the absorber on the solar cells performance. An efficiency enhancement was obtained for Cu/(In+Ga) atomic ratios between 0·93 and 0·95. The slope of the observed energy bandgap grading showed a strong influence on the V_OC and the short circuit current density J_SC. An increase of the Ga content in the active region of the absorber was achieved by the introduction of a thin Ga layer on the Mo back contact. This led to an improvement of efficiency and V_OC. Furthermore, an enhanced carrier collection was detected by quantum efficiency measurements when the absorber layer thickness was slightly decreased. Conversion efficiencies close to 10% have been obtained for these devices. Copyright © 2005 John Wiley & Sons, Ltd.     

Hierarchically porous nanoarchitecture constructed by ultrathin CoSe2 embedded Fe-CoO nanosheets as robust electrocatalyst for water oxidation

The sluggish kinetics and high cost of the noble-metal based electrocatalyst for oxygen evolution reaction(OER)still seriously limits the efficiencies of water splitting.Herein,for the first time,we rationally design a porous hierarchical nanoarchitecture,constructed by ultrathin CoSe2 embedded Fe-CoO nanosheets(CoSe2@Fe-CoO),which is synthesized via self-assembly hydrolysis driven in-situ synergetic selenization of Fe/Co/O/Se precursor followed by Ostwald ripening.As an OER catalyst,the porous CoSe2@Fe-CoO hybrid with abundant CoOOH electroactive sites delivers a small Tafel of 56.2 mV/dec with very low onset overpotential of 280 mV@10 mA/cm2 and excellent long-term physicochemical stability till 62 h without obvious decay,which outperforms well-established benchmark electrocatalysts(RuO2).The boosted OER performance of CoSe2@Fe-CoO nanosheets is mainly attributed to its iron-doping effect,porous nanoarchitecture,and multicomponent synergetic/interfacial effect between ultrathin cobalt(Ⅱ)oxide and conductive cobalt selenide(CoSe2)nanoframework.This work presents a facile construction strategy to find a nonprecious hybrid OER electrocatalyst with excellent performance and long-term stability.