Rearrangement of Epoxides to Allylic Alcohols in the Presence of Reusable Basic Resins

We have modified Merrifield’s resin to provide polymers containing secondary amine groups. Lithiation of the solids gives strongly basic yet poorly nucleophilic resins useful for rearrangement of epoxides to their corresponding allylic alcohols. The resins are easy to handle, non-volatile, non-toxic, and are easily recovered and reused, providing environmental and economic benefits that might have commercial viability.     

Drilling history and evolution at Wairakei

Drilling of the Wairakei geothermal field began in May 1950. The rigs initially used were the small truck-mounted Sullivan 37 and Failing 1500 rigs that could drill to 130 and 460 m depth, respectively. These were augmented in November 1952 with two larger capacity rigs (National T12's) that were rated to about 1500 m. The Continental Emsco GC350 was acquired in 1968 to explore the deep geothermal resource—this rig could drill to about 2500 m depth.     

Rapid radiative platinisation for dye‐sensitised solar cell counter electrodes

The successful transition of dye‐sensitised solar cell (DSC) manufacture from laboratory to factory requires new thinking in terms of lowering cost and removing time consuming manufacturing process. Platinisation of the fluorine doped tin oxide (FTO) glass counter electrode is essential for the operation of a conventional DSC and is usually carried out by thermal decomposition of chloroplatinic acid at 385 °C for 30 min. Here, near infrared radiation is used to directly heat the FTO layer resulting in full platinisation in 12.5 s. These platinised electrodes behave identically to those produced via conventional static thermal treatment in assembled DSC devices. Copyright © 2013 John Wiley & Sons, Ltd.     

Variations of Infiltration and Electronic Contact in Mesoscopic Perovskite Solar Cells Revealed by High‐Resolution Multi‐Mapping Techniques

A combination of high‐resolution mapping techniques is developed to probe the homogeneity and defects of mesoscopic perovskite solar cells. Three types of cells using a one‐step infiltration process with methylammonium lead iodide (MAPbI₃) or 5‐ammoniumvaleric acid‐MAPbI₃ solutions, or two‐step process with MAPbI₃ solution are investigated. The correlation between photoluminescence, photocurrent, electroluminescence, and Raman maps gives a detailed understanding of the different infiltration mechanisms, electronic contact at interfaces, and effect on local photocurrent for the cells. The one‐step MAPbI₃ cell has very limited infiltration of the perovskite solution which results in poor device performance. High loading of the mesopores of the TiO₂ and ZrO₂ scaffold is observed when using 5‐ammoniumvaleric acid, but some micrometer‐sized non‐infiltrated areas remain due to dense carbon flakes hindering perovskite infiltration. The two‐step cell has a complex morphology with features having either beneficial or detrimental effects on the local photocurrent. The results not only provide key insights to achieving better infiltration and homogeneity of the perovskite film in mesoporous devices but can also aid further work on planar devices to develop efficient extraction layers. Moreover, this multi‐mapping approach allows the correlation of the local photophysical properties of full perovskite devices, which would be challenging to obtain by other techniques.     

Investigating the Superoxide Formation and Stability in Mesoporous Carbon Perovskite Solar Cells with an Aminovaleric Acid Additive

Perovskite solar cells have attracted a great deal of attention thanks to their high efficiency, ease of manufacturing, and potential low cost. However, the stability of these devices is considered their main drawback and needs to be addressed. Mesoporous carbon perovskite solar cells (m‐CPSC), consisting of three mesoporous layers (TiO₂/ZrO₂/C) infiltrated with CH₃NH₃PbI₃ (MAPI) perovskite, have presented excellent lifetimes of more than 10 000 h when the additive NH₂(CH₂)₄CO₂HI (5‐ aminovaleric acid iodide; 5‐AVAI) is used to modify the perovskite structure. Yet, the role of 5‐AVAI in enhancing the stability has yet to be determined. Here, superoxide‐mediated degradation of MAPI m‐CPSC with and without the 5‐AVAI additive is studied using the fluorescence probe dihydroethidium for superoxide detection. In situ X‐ray diffractometry shows that aminovaleric acid methylammonium lead iodide (AVA‐MAPI) perovskite infiltrated in mesoporous layers presents higher stability in an ambient environment under illumination, evidenced by a slower decrease of the MAPI/PbI₂ peak ratio. Superoxide yield measurements demonstrate that AVA‐MAPI generates more superoxide than regular MAPI when deposited on glass but generates significantly less when infiltrated in mesoporous layers. It is believed that superoxide formation in m‐CPSC is dependent on a combination of competitive factors including oxygen diffusion, sample morphology, grain size, and defect concentration.     

Simple 3,6-bis(diphenylaminyl)carbazole molecular glasses as hole transporting materials for hybrid perovskite solar cells

3,6-bis(diphenylaminyl)carbazole molecular glasses were initially designed as solid hole conductor for solid-state dye-sensitized solar cells. Herein we employed these simple and easy-to-synthesize carbazole derivatives in CH₃NH₃PbI₃ regular perovskite solar cells. Devices using these hole transporting materials (HTM) gave comparable efficiency to the conventional Spiro-OMeTAD based control device made under the same conditions, thus demonstrating the huge potential of carbazole-based molecular glasses as an emerging class of lower cost organic hole conductors with easier synthetic pathways for solid state hybrid solar cells.     

Thin Film Tin Selenide (SnSe) Thermoelectric Generators Exhibiting Ultralow Thermal Conductivity

Tin selenide (SnSe) has attracted much attention in the field of thermoelectrics since the discovery of the record figure of merit (ZT) of 2.6 ± 0.3 along the b‐axis of the material. The record ZT is attributed to an ultralow thermal conductivity that arises from anharmonicity in bonding. While it is known that nanostructuring offers the prospect of enhanced thermoelectric performance, there have been minimal studies in the literature to date of the thermoelectric performance of thin films of SnSe. In this work, preferentially orientated porous networks of thin film SnSe nanosheets are fabricated using a simple thermal evaporation method, which exhibits an unprecedentedly low thermal conductivity of 0.08 W m^?1 K^?1 between 375 and 450 K. In addition, the first known example of a working SnSe thermoelectric generator is presented and characterized.