CrystEngComm Blog

The race is on to develop the most efficient, low-cost solar cells to meet the green energy demand of the future. Unfortunately, high power conversion efficiencies often come at high economic cost and so there is still a lot of room for improvement for existing materials and technologies.

Scientists from Donghua University, China, have now touched upon another desirable feature of solar cell materials – environmentally friendly synthesis. Junqing Hu and his team have sought to develop solar cells based on Cu₂ZnSnS₄ (CZTS) nanocrystal films.

Previous reports using these nanocrystal inks or the selenised CZTSSe analogues have shown promise but their hydrophobic nature (due to the oleylamine capping agent) means they can only be dispersed in organic solvents. Other drawbacks to their synthesis include using cadmium in the buffer layer (environmental implications); glass substrates (inflexibility); and hydrazine as a precursor to the inks (toxic and difficult to handle).

In their recent CrystEngComm Communication, Hu and colleagues describe the solvothermal synthesis of hydrophilic CZTS nanocrystal inks. By developing a film-printing technique they were able to fabricate a flexible and environmentally-friendly solar cell. Although the conversion efficiency is somewhat low (1.94 %) compared to other reported values for CZTSSe materials, the authors expect that it can be improved by optimising the film-printing technique, film thickness and annealing process, and selenising the film.

This HOT article is free to access until 19^th March so download it now…

Hydrophilic Cu₂ZnSnS₄ nanocrystals for printing flexible, low-cost and environmentally friendly solar cells
Qiwei Tian,  Xiaofeng Xu,  Linbo Han,  Minghua Tang,  Rujia Zou,  Zhigang Chen,  Muhuo Yu,  Jianmao Yang and Junqing Hu

Perovskite materials are pretty tricky to synthesise – particularly those with A_xA_1–x‘BO₃ structure. Conventional solid state approaches suffer from contamination with unreacted materials and even sol-gel processes can result in materials with structural defects and impurities.

Chi-Young Lee and co-workers from National Tsing Hua University in Taiwan have set out to find a simpler route to synthesise these troublesome materials, developing a chemical method that requires the lowest temperature reported to date for perovskite synthesis.

Their method involves mixing TiO₂ with the desired Group 2 hydroxide in sodium hydroxide solution and refluxing at 140 °C. By varying the reaction time, they were able to control the morphology as they demonstrated for SrTiO₃, attributing the different forms to the relative stabilities of the crystal planes. What’s more, they could tune the composition of Ba_xSr_1–xTiO₃ through stoichiometric adjustment of the starting materials.

To find out more on Lee and his team’s perovskite synthesis, download the CrystEngComm article today…
Simple chemical preparation of perovskite-based materials using alkali treatment

Also of interest…

• Local structural distortion of BaZr_xTi_1–xO₃ nanocrystals synthesized at room temperature, F. A. Rabuffetti and R. L. Brutchey, Chem. Commun., 2012, 48, 1437.
• Low-temperature synthesis of solid-solution Ba_xSr_1–xTiO₃ nanocrystals, R. L. Brutchey et al., J. Mater. Chem., 2010, 20, 5074.

The crystal structures and packing of organic compounds in the solid state are determined by the types of bonds between the molecules, the structure will depend upon the number, strength and orientation of inter-molecular interactions and bonds. Piyush Panini and Deepak Chopra of IISER Bhopal looked to investigate this further by synthesising, characterising and crystallising a series of 10 isomeric mono and di-trifluoromethylated benzanilides.

While the traditional C–H  –  –  –  O/N type hydrogen bonds are well studied it is more difficult to evaluate some of the weaker interactions, such as those involving halogens. In this Hot Article the authors look to link the cooperative effects of some of the weaker interactions to crystal structures and packing motifs, making some interesting discoveries.

All hot articles are free to access in CrystEngComm for 4 weeks, so you can download this article for free until next month by clicking the link below.

Role of intermolecular interactions involving organic fluorine in trifluoromethylated benzanilides
Piyush Panini and Deepak Chopra
CrystEngComm, 2012, Advance Article
DOI: 10.1039/C2CE06254B

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In this HOT Article, the achiral mesoxalato ligand (H₂mesox^2-) is identified as a new enantiopurity enforcer in extended structures by yielding the homochiral metal-organic frameworks (MOFs) 2D-[Ln₂(µ-H₂mesox)₃(H₂O)₆]. The chirality of the compounds can be observed in the features of the crystal structure and also in the dominating intensity of the hypersensitive transition within trivalent europium, which reacts strongly to the absence of a local inversion centre and proves the chiral environment of the rare-earth ions within the complexes.

Read more for FREE about MOFs at:

Homochiral lanthanoid(III) mesoxalate metal–organic frameworks: synthesis, crystal growth, chirality, magnetic and luminescent properties
Beatriz Gil-Hernández, Jana K. Maclaren, Henning A. Höppe, Jorge Pasán, Joaquín Sanchiz and Christoph Janiak
CrystEngComm, 2012, Advance Article
DOI: 10.1039/C2CE06496K

PbSe nanorods have been successfully made by solution–liquid–solid (SLS) growth of PbSe nanocrystals. This growth was followed by oriented attachment of adjacent PbSe nanoparticles. The team from South Korea who carried out this synthesis used Bi catalysts dispersed in the precursor solution to make these nanocrystals thereby reducing the time and temperature taken to produce them.

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Enhanced formation of PbSe nanorods via combined solution–liquid–solid growth and oriented attachment
Min-Seok Kim and Yun-Mo Sung
CrystEngComm, 2012, DOI: 10.1039/C2CE06353K

Cerium is an interesting element for luminescence, however only Ce³⁺ ions give rise to fast luminescence because the charge transfer transition in Ce⁴⁺ is spin-forbidden. Ce-doped lutetium scandium orthoborate (Lu_0.8Sc_0.2BO₃:Ce) has potential application in gamma-ray detection and in this Hot Article by Yuntao Wu and Guohao Ren et al. (Shanghai Institute of Ceramics, Chinese Academy of Sciences) the oxidation state of the Ce ions is investigated.

The study on single crystals of Lu_0.8Sc_0.2BO₃:Ce utilizes XANES based on new generation synchrotron radiation. The research team were able to discover the influence cerium doping has on the luminescence mechanism and the type of point defect in Lu_0.8Sc_0.2BO₃:Ce crystals.

This Hot Article is free to access for 4 weeks and you can keep up to date with the latest news in crystal engineering by liking us on facebook, following us on twitter or signing up to our e-alert service!

Investigation on the influence of cerium doping form on the luminescence properties of Lu_0.8Sc_0.2BO₃ scintillation crystals
Yuntao Wu, Guohao Ren, Dongzhou Ding, Fan Yang and Shangke Pan
CrystEngComm, 2012, Advance Article
DOI: 10.1039/C2CE06332H, Paper

Co-crystallisation of nevirapine with maleic acid lead to around a fivefold increase in the aqueous solubility of the drug.

Mino Caira and colleagues have created co-crystals of nevirapine (an antiretroviral drug) with maleic acid that could improve the aqueous solubility of the drug.  Their success was a result of exploiting several hydrogen-bonding functionalities in nevirapine, in particular (but not exclusively) its rigid amide group.

Read their paper to find out more – its currently free.

Co-crystals of the antiretroviral nevirapine: crystal structures, thermal analysis and dissolution behaviour
Mino R. Caira, Susan A. Bourne, Halima Samsodien, Emile Engel, Wilna Liebenberg, Nicole Stieger and Marique Aucamp
CrystEngComm, 2012
DOI: 10.1039/C2CE06507J