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The long-term performance stability of organic solar cells (OSCs), as well as their high power-conversion efficiency, is necessary for their practical use. A stable OSC with the structure of ITO/buffer/donor/acceptor/cathode is presented. A thin layer of MoO3-doped PTCDA (molar ratio 1:1) is adopted as the buffer in CuPc/C60 organic heterojunction photovoltaic (PV) solar cells, resulting in four to five times longer lifetime. The CT complex of buffer layer plays a decisive role in improving the stability and abnormal efficiency changes. [ABSTRACT FROM AUTHOR]

Abstract: A stable organic solar cell with structure of ITO/buffer/donor/acceptor/cathode is presented. A thin layer (5nm) of MoO3-doped CuPc is adopted as the buffer in CuPc/C60 organic heterojunction photovoltaic (PV) solar cells, resulting in two times longer lifetime. The surface morphology of buffer layer plays a decisive role in improving the stability. [Copyright &y& Elsevier]

High-performance vanadium dioxide (VO 2) thin films with high luminous transmittance and solar modulation ability were successfully fabricated on Zr x O y /glass substrate by pulsed laser deposition. By controlling the growth temperature of the buffer layer, the stoichiometry and crystal structure of Zr x O y buffer layer can be converted from cubic Zr 2 O phase to monoclinic ZrO 2 phase. Through such a transformation, the luminous transmittance (T lum), solar modulation ability (Δ T sol), the transition temperature and the width of thermal hysteresis loop have been tuned without diminishing the thermochromic property. It is found that the insertion of ZrO 2 layer results in a remarkable enhancement of the luminous transmittance and the solar modulation ability when compared to single-layer VO 2 film. The findings in the present work may provide some new strategies for the commercialization of VO 2 films in the field of smart energy-efficient windows. • The ZrO2 film with monoclinic crystal structure was used as the buffer layer in the preparation of high-quality VO2 films by Pulsed Laser Deposition. • The glass/ZrO2/VO2 composite films with impressive photoelectric properties were obtained. [ABSTRACT FROM AUTHOR]

Highlights • We present a new approach to change the polymorph of VO 2 from VO 2 (B) to VO 2 (M) by inserting TiO 2 buffer layers. • The origin of the transformation property was discussed in detail. • The thickness of TiO 2 buffer layers were optimized. • The VO 2 /TiO 2 /glass composite films with impressive photoelectric properties were obtained. Abstract Vanadium dioxide (VO 2) with reversible metal–insulator transition (MIT) is a promising energy-saving material for next-generation smart windows and infrared devices. However, the specific applications are largely limited by controllable preparation with different polymorphs on common glass substrates. Herein, VO 2 thin films were prepared on transparent amorphous glass substrates by inserting TiO 2 buffer layers using pulsed laser deposition (PLD) technique. The results showed that B-VO 2 film would be formed on the amorphous glass substrate at 400 °C. While after inserting TiO 2 buffer layer, pure M-VO 2 films with clear phase transition properties were obtained. Based on the analysis of X-ray Diffraction (XRD) and Energy Dispersive Spectrometer (EDS) characterization, the crystalline transformation was attributed to the template effect of TiO 2 layer and Ti ions diffusion. The characteristics of VO 2 /TiO 2 /glass thin films were closely associated with the thickness of TiO 2 buffer layer. With 60 nm TiO 2 buffer layer, the VO 2 /TiO 2 /glass film showed the sharpest resistance change with more than 2.5-order of magnitude across the MIT, and the T-vis value is as high as 53% with the Δ T sol up to 5.2%. Our current results demonstrated the importance of TiO 2 buffer layer to the formation of M-VO 2 film on amorphous glass substrate, which was very meaningful for the production of energy efficient smart windows in the future. [ABSTRACT FROM AUTHOR]

• High quality SnO 2 /VO 2 bi-layer films are prepared by pulsed laser deposition. • The grain size and roughness of VO 2 can be regulated by SnO 2 buffer layer. • Balance between luminous transmittance and solar modulation ability is achieved. For decades, the practical application of VO 2 -based smart windows is limited by its low luminous transmittance (T lum) and solar modulation ability (ΔT sol). In this study, SnO 2 /VO 2 thermochromic thin films were produced on amorphous glass substrates via pulsed laser deposition and were characterized by x-ray diffraction, scanning electron microscopy, atomic force microscopy, spectrophotometry, and resistance measurements. By adjusting the thickness of SnO 2 buffer layer, not only the semiconductor-to-metal transition temperature of VO 2 films can be effectively tuned, but also the T lum and ΔT sol of VO 2 films can be increased synchronously to 54.9% and 8.3%, respectively. It is shown that the grain size of VO 2 films increases from ~15 nm to ~90 nm with the SnO 2 buffer layer thicknesses increase from 25 nm to 125 nm, and consequently the electrical and optical properties of VO 2 films are effectively improved. These can be attributed to the fact that SnO 2 buffer layer can effectively control the grain size, surface roughness and optical band gap of VO 2.The results suggest that the SnO 2 buffer layer is very beneficial for the growth of high-quality VO 2 films on glass substrates, which is of importance for the application of VO 2 in energy-efficient smart windows. [ABSTRACT FROM AUTHOR]

In this study, high-quality thermochromic vanadium dioxide (VO 2) thin films were grown on ZrO 2 /glass by pulsed laser deposition and were investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), double beam spectrophotometry and Hall Effect measurement system. Based on XRD results, it can be inferred that the crystal structure of ZrO 2 buffer layer can be transformed between monoclinic and tetragonal structures with the increase of buffer layer thickness. Photoelectric performance tests showed that the introduction of ZrO 2 buffer layer considerably reduced the phase transition temperature (T c) and hysteresis loop width (Δ H) of the VO 2 films and allowed the visible light transmittance (T lum) and solar modulation ability (Δ T sol) of the films to be tuned effectively. Especially, when the thickness of the ZrO 2 buffer layer was 50 nm, the T c of the VO 2 films reached the minimum value of 48 °C. When the ZrO 2 buffer layer thickness increased to 125 nm, the sheet resistance change of the VO 2 film attained two orders of magnitude, and their T lum-90°C and Δ T sol were as high as 50.01% and 7.88%, respectively. These results showed that the ZrO 2 buffer layer considerably affected the growth of VO 2 films on amorphous glass substrates and was beneficial for the application of VO 2 in energy-saving smart windows. [ABSTRACT FROM AUTHOR]