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Li J.,CAS Shanghai Institute of Applied Physics | Chao J.,CAS Shanghai Institute of Applied Physics | Chao J.,Institute of Advanced Materials IAM | Shi J.,UCB Pharma | Fan C.,CAS Shanghai Institute of Applied Physics
ChemBioChem | Year: 2015

A very attractive goal in nanotechnology is to manufacture smart nanodevices that integrate multiple biological/biomedical functions and autonomously function in vivo in a predefined and well-controlled manner. For decades, researchers have been developing many different ways toward this target, using bottom-up assembly of types of nanomaterials or top-down fabrication of devices with nanometer-scale precision. However, the practical application of these nanodevices remains challenging. One possible barrier lies in the spatiotemporal separation between fabrication and use, which poses a great challenge for the non-invasive delivery of fully functional nanodevice into live cells. Indeed, cells themselves are highly complex natural machines with membrane barriers and finely regulated pathways for intracellular delivery. However, there is plenty of evidence that nanomaterials or nanodevices are easily aggregated or trapped inside of the cells. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

He H.,Zhejiang University | Yu Q.,Zhejiang University | Li H.,Zhejiang University | Li J.,Zhejiang University | And 8 more authors.
Nature Communications | Year: 2016

Organolead trihalide perovskites have attracted great attention due to the stunning advances in both photovoltaic and light-emitting devices. However, the photophysical properties, especially the recombination dynamics of photogenerated carriers, of this class of materials are controversial. Here we report that under an excitation level close to the working regime of solar cells, the recombination of photogenerated carriers in solution-processed methylammonium-lead-halide films is dominated by excitons weakly localized in band tail states. This scenario is evidenced by experiments of spectral-dependent luminescence decay, excitation density-dependent luminescence and frequency-dependent terahertz photoconductivity. The exciton localization effect is found to be general for several solution-processed hybrid perovskite films prepared by different methods. Our results provide insights into the charge transport and recombination mechanism in perovskite films and help to unravel their potential for high-performance optoelectronic devices.

Wu J.,Nanyang Technological University | Yu C.-H.,National University of Singapore | Li S.,Nanyang Technological University | Li S.,Nanjing University of Posts and Telecommunications | And 14 more authors.
Langmuir | Year: 2015

Developing a cost-effective nanolithography strategy that enables the production of subwavelength features with various shapes over large areas is a long-standing goal in the nanotechnology community. Herein, an inexpensive nanolithographic technique that combines the wafer-scale production capability of photolithography with the subwavelength feature size controllability of near-field photolithography was developed to fabricate centimeter-scale up to wafer-scale sub-100-nm variously shaped nanopatterns on surfaces. The wafer-scale elastomeric trench-based photomasks with subwavelength apertures created at the apexes were compatible with mask aligners, allowing for the production of wafer-scale subwavelength nanopatterns with adjustable feature sizes, shapes, and periodicities. The smallest feature sizes of 50 and 80 nm were achieved on positive tone and negative tone photoresist surfaces, respectively, which could be ascribed to a near-field optical effect. The fabricated centimeter-scale nanopatterns were functionalized to study cell-matrix adhesion and migration. Compared to currently developed nanolithographic methods that approach similar functionalities, this facile nanolithographic strategy combines the merits of low cost, subwavelength feature size, high throughput, and varied feature shapes, making it an affordable approach to be used in academic research for researchers at most institutions. © 2014 American Chemical Society.

Ou C.-J.,Nanjing University of Posts and Telecommunications | Ou C.-J.,Institute of Advanced Materials IAM | Lei Z.-F.,Nanjing University of Posts and Telecommunications | Sun M.-L.,Nanjing University of Posts and Telecommunications | And 5 more authors.
Synthetic Metals | Year: 2015

The number of bulky groups in hindrance-capped π-systems is closely relative to thin film morphology, stability and luminescent features in printing electronics. Herein, we demonstrated advantages of dumbbell-shape over mono-substituted organic semiconductors by designing two highly bulky 3′,6′-bis(octyloxy) spiro[fluorene-9,9′-xanthene] (OSFX)-functionalized pyrene derivatives, OSFXPy and DOSFXPy. Their differences in terms of thermal, photophysical and electrochemical properties, and film morphologies were characterized via thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), UV-vis absorption and photoluminescence (PL), cyclic voltammetry and atomic force microscopy (AFM). DOSFXPy has higher thermal and electrochemical stability, more suitable energy levels and smaller bandgap than that of OSFXPy. Thin film of DOSFXPy is smooth and pin-hole free, while OSFXPy is easy to crystallize and form large crystal domains. Solution-processed nondoped electroluminescent devices based on DOSFXPy exhibit stable deep-blue emission with excellent CIEx,y color coordinates (x = 0.15, y = 0.13) at the luminance of 1000 cd/m2, and the maximum luminance of up to 3200 cd/m2 and maximum current efficiency of 2.07 cd/A, respectively. Moreover, solution-processed doped OLEDs with DPAVBi show greenish-blue emission with optimum current efficiency of 4.52 cd/A at doping concentration of 3 wt%. © 2015 Elsevier B.V. All rights reserved.

Li L.,Molecular Devices | Hu T.-Q.,Molecular Devices | Yin C.-R.,Institute of Advanced Materials IAM | Xie L.-H.,Molecular Devices | And 7 more authors.
Polymer Chemistry | Year: 2015

Hindrance functionalization at the reactive sites makes π-stacked polymers highly stable for applications related to organic electroluminescent devices. Herein, a novel stable polymer host material, poly(3,6-bis- (9-phenylfluoren-9-yl)-9-vinyl-carbazole) (PVKDPF), has been designed and synthesized from dumbbell-shaped monomers by introducing two bulky 9-phenylfluorenyl moieties (PFMs) to the carbazole units. PVKDPF, with a high triplet energy level of 2.85 eV, shows outstanding thermal and morphological stability. Interestingly, as compared to its precursor, poly(N-vinylcarbazole) (PVK), PFMs-capped PVKDPF shows enhanced anti-photoaging against UV light, along with a much better electrochemical stability, without any obvious change even after repeated scanning during cyclic voltammetry. The prototype blue phosphorescent polymer light-emitting devices (PhPLEDs) using PVKDPF as the host and doped with the FIrpic guest exhibit excellent blue electroluminescence with the Commission Internationale de L'Eclairage (CIE) coordinate of (0.184, 0.381), luminous efficiency corresponding to 17.3 cd A-1, and power efficiency corresponding to 9.0 lm W-1. Hindrance-capped dumbbell-shaped polymers are robust polymer semiconductors that can be used in mechatronic devices. © The Royal Society of Chemistry 2015.

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