Tartaric acid additive to enhance perovskite multiple preferential orientations for high-performance solar cells

Perovskite film quality is a decisive factor governing the performance and long-term stability of perovskite solar cells(PSCs). To passivate defects for high-quality perovskite films, various additives have been explored in perovskite precursor with notable achievements in the development of highperformance PSCs. Herein, tartaric acid(TA) was applied as additive in perovskite precursor solution to modulate the crystal growth leading to high quality thin films with enhanced multiple preferential orientations favoring efficient charge transport along multiple directions. It is also noticed that TA can improve the energy level alignment in PSCs, which effectively accelerates both carrier extraction and transportation with non-radiative recombination suppressed at the perovskite interfaces. Based on the present perovskite films, the fabricated PSCs achieved an excellent champion power conversion efficiency(PCE) of 21.82% from that of 19.70% for the control device without TA additive. In addition, a PSC with TA additive was shown to exhibit impressive operational stability by retaining 92% of its initial PCE after~1200 h of aging at room temperature in ambient air with a relative humidity of about 10%–25%. In summary, the present work demonstrates a facile and versatile approach by using TA as additive in perovskite precursor to fabricate high quality perovskite films with enhanced multiple preferential orientations for high-efficiency stable PSCs.

A Study of AlN Films Prepared by Arc Ion Plating

Hexagonal AIN films have been obtained by arc ion plating at different negative biases. X-ray diffraction and scanningelectron microscopy results show that AIN films with smooth surfaces and (002) preferred orientation are obtainedat low biases, whereas those with coarse surfaces and (100) preferred orientation are obtained at high biases. Theformation mechanism of AIN is analyzed and the experiment results are discussed. The effect of bias on adhesionstrength has also been examined.

Structural and Magnetic Properties of Electrodeposited Ni_(70)Fe_(30) Nanowire Array

Ordered Ni70Fe30 nanowire array was fabricated in a porous alumina template by alternating current electrodeposition. The structural and magnetic properties of the as-obtained nanowire array were investigated by SEM, TEM, XRD, EDS and VSM. The results indicate that the as-obtained Ni70Fe30 nanowires exhibit a diameter of about 69.9 nm and aspect ratio of more than 60. Meanwhile, a preferred orientation [110] of bcc lattice was observed. The as-obtained nanowire array has an obvious magnetic anisotropy, of which the easy direction is perpendicular to the surface of the array. Moreover, after annealed, the Ni70Fe30 nanowire array exhibits an enhanced magnetic anisotropy.

Oxygen vacancy self-doped single crystal-like TiO_(2) nanotube arrays for efficient light-driven methane non-oxidative coupling

Photocatalytic non-oxidative coupling of methane(PNOCM)is a mild and cost-effective method for the production of multicarbon compounds.However,the separation of photogenerated charges and activation of methane(CH4)are the main challenges for this reaction.Here,single crystal-like TiO_(2) nanotubes(VO-p-TNTs)with oxygen vacancies(VO)and preferential orientation were prepared and applied to PNOCM.The results demonstrate that the significantly enhanced photocatalytic performance is mainly related to the strong synergistic effect between preferential orientation and VO.The preferential orientation of VO-p-TNT along the[001]direction reduces the formation of complex centers at grain boundaries as the form of interfacial states and potential barriers,which improves the separation and transport of photogenerated carriers.Meanwhile,VO provides abundant coordination unsaturated sites for CH4 chemisorption and also acts as electron traps to hinder the recombination of electrons and holes,establishing an effective electron transfer channel between the adsorbed CH4 molecule and photocatalyst,thus weakening the C–H bond.In addition,the introduction of VO broadens the light absorption range.As a result,VO-p-TNT exhibits excellent PNOCM performance and provides new insights into catalyst design for CH4 conversion.

Effects of Sn-doping on morphology and optical properties of CdTe polycrystalline films

Sn-doped CdTe polycrystalline films were successfully deposited on ITO glass substrates by close space sublimation. The effects of Sn-doping on the microstructure, surface morphology, and optical properties of polycrys- talline films were studied using X-ray diffraction, scanning electron microscopy, and ultraviolet-visible spectrophotometry, respectively. The results show that the lower molar ratio of Sn and CdTe conduces to a strongly preferential orientation of （111） in films and a larger grain size, which indicates that the crystallinity of films can be improved by appropriate Sn-doping. As the molar ratio of Sn and CdTe increases, the preferential orientation of （111） in films becomes weaker, the grain size becomes smaller, and the crystal boundary becomes indistinct, which indicates that the crystallization growth of films is incomplete. However, as the Sn content increases, optical absorption becomes stronger in the visible region. In summary, a strongly preferential orientation of （111） in films and a larger grain size can be obtained by appropriate Sn-doping （molar ratio of Sn ： CdTe = 0.06 ： 1）, while the film retains a relatively high optical absorption in the visible region. However, Sn-doping has no obvious influence on the energy gap of CdTe films.