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Silica-based coatings prepared using sol-gel polymerizing technology have been shown to exhibit excellent chemical stability combined with reducing the corrosion of metal substrates, showing promising use in aerospace and marine applications to protect light alloys. Moreover, this technology is an eco-friendly technique route for producing surface coatings, showing high potential for replacing toxic pre-treatment coatings of traditional conversation chromate coatings. This study aims to investigate the enhancement in corrosion protection of a hybrid-organic-inorganic silica-based coating cured at 80 °C by increasing the hydrophobicity to work on the aluminium 2024-T3 alloy. This approach involving a novel silica-based hybrid coating was prepared by introducing 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES) into the base hybrid formula created from tetraethylorthosilicatesilane (TEOS) and triethoxymethylsilane (MTMS) precursors; this formula was enhanced by introducing a Polydimethylsiloxane polymer (PDMS). The corrosion protection properties of these coatings were examined by being immersed in 3.5% NaCl with electrochemical impedance testing (EIS) and Potentiodynamic polarization scanning (PDPS). The chemical elements confirmation was performed using infrared spectroscopy (ATR-FTIR); all this was supported by analysing the surface morphology before and after the immersion by using scanning electron microscopy (SEM). The results of the electrochemical impedance testing analyses reveal the new open finite-length diffusion circuit element due to electrolyte media diffusion prevented by fluorinated groups. Additionally, it shows increases in corrosion protection arising from the increasing hydrophobicity of the fluorinated coating compared to other formulas cured under similar conditions and bare substrate. Additionally, the modified sol-gel exhibited improved resistance to cracking, while the increased hydrophobicity may also promote self-cleaning.

Perovskite solar cells have shown an impressive efficiency improvement over the past ~ 10 years achieving ~ 23% to date. However, the lifetime and instability of device characteristics are real issues to understand and solve before scaling up and commercialisation of these devices. Researchers have attempted to understand the hysteresis behaviour of current–voltage (I–V) curves in terms of mechanisms such as migration of several ions across the device and the effects of electronic defects during measurements. This review contributes to this scientific debate by presenting similar behaviour observed and reported for devices based on inorganic semiconductors. In established inorganic semiconductor thin film solar cells, both short lifetime and hysteresis have been observed, described and understood in terms of effects of numerous electronic defect levels. Therefore, the situation may be very similar and it is important to identify and reduce defects to remove this un-desirable behaviour from perovskite solar cells. After considering the wealth of experimental results reported in the literature, the conclusion made is the dominating mechanism of I–V hysteresis is due to electronic defects available within the device structure. Suggestions have been made for potential researchers to experimentally investigate the phenomenon in order to finally put an end to this debate. As the defect levels and their concentrations are reduced, the initial efficiency, stability and the lifetime of perovskite solar cells should improve further, beyond the current situation.

— Sol-gel as protective coatings has been shown to exhibit excellent chemical stability combined with the ability to reduce the corrosion of metal substrates. The sol-gel method is an eco-friendly technique route for producing surface coatings, showing high potential for the replacement of toxic pre-treatment coatings. This study aims to develop a new understanding of the enhancement in corrosion protection of a hybrid-organic-inorganic sol-gel coating that cured at (80oC) by increasing the hydrophobicity and characterized the performance on the aluminium 2024-T3 alloy. The alternative method involved a novel sol-gel was prepared by introducing a1H,1H,2H,2Hperfluorodecyltriethoxy silane (PFDTES) into the base hybrid sol-gel created from tetraethylorthosilicate silane (TEOS) and triethoxymethyl silane (MTMS) precursors. The results of electrochemical testing analyses reveal the new open finite-length diffusion circuit element (O) coming from electrolyte media diffusion preventive by fluorinated groups. Also, it is revealed increases in corrosion protection arising from the increasing the hydrophobicity of the fluorinated sol-gel coating when it compared to other formula cured under similar conditions. Additionally, the modified sol-gel exhibited improved resistance to cracking, while the increased hydrophobicity may also promote self-cleaning

Perovskite solar cells exhibiting~14–15% efficiency were experimentally measured using current–voltage (I–V) and capacitance–voltage (C–V) techniques in order to extract material and device properties, and understand the action of photovoltaic\ud (PV) operation. Deep analyses were carried out on dark- and illuminated I–V curves, and dark C–V curves. Results were\ud compared with those of graded bandgap solar cells fabricated on inorganic n-type window layers. These analyses according\ud to a physicist’s point of view lead to understand the perovskite solar cell as a graded bandgap solar cell built on a p-type\ud window layer. I–V and C–V results show very similar behaviour and the principle of PV action is identical. Once the stability\ud issues with perovskites are solved, these devices have very high potential of producing next generation solar cells reaching\ud at least mid-20% efficiency values.

The optical transmittance, electrical conductivity and morphology of PEDOT:PSS treated with ammonium hydroxide (NH4OH) have been investigated. Transmittance spectra of spun PEDOT:PSS layers were enhanced slightly as a result NH4OH treatment while surface of the films has exhibited variation in the roughness and an increase in the electrical conductivity. Improvement in the physical properties of PEDOT:PSS is shown to be the key factor in enhancing the power conversion effeciency (PCE) with values as high as 4% associated with high fill factor (FF) of 57%, open circuit voltage (VOC) of 0.64 V and larger short circuit current density (JSC) of 11 mA cm−2. Stabiltiy test of the devices has been carried out over a period of 2 months, when a device incorporating PEDOT:PSS with pH ~ 4 as the hole transport layer has shown an improved stability with a degredation in PCE in about 43% whereas JSC has decreased in about 20% compared to a device incorporating pristine PEDOT:PSS with PCE decreased in about 66% and JSC in about 50% over the stated period of test. These effects have been ascribed to the increased acidity of the hole transport layer.

Organic-inorganic halide perovskites are one of the most attractive materials for the next generation solar cells. The PCE has rapidly increased to more than 22% using different configurations and techniques and further developments are predicted. However, perovskite solar cells suffer from fabrication reproducibility mainly due to difficulty in controlling the morphology of the perovskite films themselves. In this paper we present a low temperature solution-processed two-step deposition method to fabricate CH3NH3PbI3 perovskites. This method offers a simple route with great potential in fabricating reproducible perovskite solar cells. In the present work, we demonstrate that the morphology of the perovskite thin films is highly determined by the concentration of Methylammonium iodide (MAI) as well as the reaction time between MAI and PbI2. High-performance solar cells have been reproducibly achieved with a highest PCE of 15.01% for PCBM-based planar heterojunction solar cells.

All solution processable photovoltaic (PV) devices have been great interests in the past decade and different processing methods have been explored to produce the PV devices. In this paper, the dip-coating method was studied to fabricate core layers in the inverted polymer photovoltaic devices, which demonstrates that the dip-coating technology has its potential to produce large area PV devices. The crystallinity of the active layers by the dip-coating method can be improved under the condition of the extended drying rate. Light absorption spectra and X-ray diffraction (XRD) patterns of the active layers were investigated to confirm the improved crystallinity of the active layers. Various morphologies of the dip-coated layers were observed by the atomic force microscopy (AFM). The best PV device achieved ∼3.4% power conversion efficiency.

A new route for fabrication of photoactive materials in organic-inorganic hybrid solar cells is presented in this report. Photoactive materials by blending a semiconductive conjugated polymer with an organolead halide perovskite were fabricated for the first time. The composite active layer was then used to make planar heterojunction solar cells with the PCBM film as the electron-acceptor. Photovoltaic performance of solar cells was investigated by J-V curves and external quantum efficiency spectra. We demonstrated that the incorporation of the conjugated photoactive polymer into organolead halide perovskites did not only contribute to the generation of charges, but also enhance stability of solar cells by providing a barrier protection to halide perovskites. It is expected that versatile of conjugated semi-conductive polymers and halide perovskites in photoactive properties enables to create various combinations, forming composites with advantages offered by both types of photoactive materials.