Durable metal-enhanced fluorescence flexible platform by in-situ growth of micropatterned Ag nanospheres

Here, we demonstrate an in-situ growth of micropatterned silver nanospheres(Ag NS) array on transparent polyimide(PI), namely PI-Ag substrate, applied as a flexible platform for metal-enhanced fluorescence(MEF). The scheme proposed here can easily control the grid formation of Ag NSs and the particle size inside, thus achieving patterned fluorescence imaging and MEF efficiency optimization. Meanwhile, the magnitude of enhanced intensity, relying on the distance between Ag NSs and emissive molecules, was systematically investigated by exploring diverse polyethyleneimine(PEI) spacer thickness. Consequently,an optimal enhancement factor of 7.9 and a pattern of grid fluorescence imaging was obtained with an insertion of 10 nm PEI on the PI-Ag(25 nm) platform. Moreover, owing to robust adhesion between Ag NSs and PI film by in-situ growth, this flexible PI-Ag MEF platform maintained a stable MEF efficiency even after taking mechanical bending for 1000 cycles. This new surface-confined micropatterned Ag NSs PI film provides a promising candidate in design flexible MEF platforms for future analytical and clinical sensing applications.

Side chains and backbone structures influence on 4,7-dithien-2-yl-2,1,3-benzothiadiazole （DTBT）-based Iow-bandgap conjugated copolymers for organic photovoltaics

Five 4,7-dithien-2-yl-2,1,3-benzothiadiazole （DTBT）-based conjugated copolymers with controlled molecular weight were synthesized to explore their optical, energy level and photovoltaic properties. By tuning the positions of hexyl side chains on DTBT unit, the DTBT- fluorene copolymers exhibited very different aggregation properties, leading to 60 nm bathochromic shift in their absorptions and the corresponding power conversion efficiencies （PCEs） value of photovoltaic cells varied from 0.38%, 0.69% to 2.47%. Different copolymerization units, fluorene, earbazole and phenothiazine were also investigated. The polymer based on phenothiazine exhib- ited lower PCE value due to much lower molecular weight owing to its poor solubility, although phenothiazine units were expected to be a better electron donor. Compared with the fluorene-based polymer, the carbazole-DTBT copolymer showed higher short circuit current density （Jsc） and PCE value due to its better intermolecular stacking,

Growth mechanism of CsPbBr3 perovskite nanocrystals by a co-precipitation method in a CSTR system

A co-precipitation method based on supersaturated recrystallization in a continuous stirred-tank reactor(CSTR)system was applied to un cover the growth mecha nism of CsPbBr3 perovskite nano crystals(NCs).The reacti on rate can be controlled by changi ng the reaction conditions in this CSTR system,which helps us to observe importa nt intermediate stages to gain in sight into the growth mecha nism of these NCs.The effects of the temperature,concentrations of the ligands(oleylamine and oleic acid),and precursor concerttrations during the growth process of CsPbBr3 NCs were discussed in detail.Further,the growth mechanism of CsPbBr3 NCs was investigated in terms of the dynamics and thermodynamics on the basis of experimental results.The growth mechanism is a useful guide to large-scale synthesis.The synthesized CsPbBr3 NCs were employed for fabrication of both white light-emitting diodes and quantum-dot light-emitting diodes to test their photoelectric properties;the results show that CsPbBr3 NCs show great promise for optoelectronics applications.

Plasmon-induced near-field and resonance energy transfer enhancement of photodegradation activity by Au wrapped CuS dual-chain

Self-assembled chain-like nanostructures utilizing localized surface plasmon resonance(LSPR)effect could enhance the local electromagnetic field for energy transfer,which provides huge structural advantages for some transmission-related applications such as photocatalysis.In this work,the dual-chain structure of Au chain wrapped CuS(denoted as Au Chain@CuS)was successfully synthesized by the one-step hydrothermal method.Namely,L-cysteine is used as the sulfur source and linking agent,and copper nitrate is the precursor of copper ions,forming the dual-chain driven by 15 nm uniform Au seeds.Transient absorption spectroscopy(TAS)and finite-difference-time-domain(FDTD)simulation exhibited the highly intensive electromagnetic field around the self-assembly chain,the raised formation and transfer rate of electron–hole pairs between the Au chain and surrounding CuS chain.Meanwhile,it shows an excellent photodegradation activity on dye rhodamine B(RhB).Within 1 h under simulated sunlight,the degradation rate reached 98.81%in Au Chain@CuS,which is 2.27 times higher compared to the bare CuS.The enhanced performance is mainly attributed to the near-field enhancement effect induced by LSPR,as well as the benefits of more effective resonance energy transfer(RET).This research comprehensively shows the electromagnetic field in LSPR metal chain is more intensive by order of magnitude relative to the isolated particles.Simultaneously the continuous CuS chain wrapped outside of the LSPR source effectively absorbs and utilizes the plasmonic energy,then promotes the formation of the photo-generated charge,thus increasing the photocatalytic performance.This founding of wrapped coupled-metal dual-chain provides a promising candidate for the highly efficient photocatalysts.

Synthesis of two A-B-C type conjugated amphiphilic triblock fullerene derivatives and their application in organic solar cells

Two A-B-C type conjugated amphiphilic triblock fullerene derivatives C60-2 HMTPB and C60-2 EHTPB were obtained in multi steps synthesis with three different blocks,and the amphiphilic diblock molecular C60-4 TPB was also preferred as a reference.When as modifying layer on zinc oxide(ZnO),the three fullerene derivatives can all reduce the work function of ZnO via modulation of the interfacial dipoles and lead a better electrical coupling.As introducing treatment of toluene,the obvious self-assembly of fullerene derivatives were observed,which were supported by X-ray diffraction and contact angle of water measurement.Base on PTB7-Th:PC71 BM system,the inverted organic solar cells devices with structure of ITO/ZnO/fullerene derivatives/PTB7-Th:PC71BM/Mo03/Al got power conversion efficiencies of 8.62%,8.83%and 9.00%for C60-4 TPB,C60-2 HMTPB and C60-2 EHTPB,respectively,compared 8.13%of devices with bare ZnO.The result of conjugated amphiphilic triblock fullerene derivatives provides a straightforward approaching by simultaneously modulating the morphology and interfacial work function of ZnO,which can also lead high performance in optoelectronic devices.

Indium tin oxide-free inverted polymer solar cells with ultrathin metal transparent electrodes

Efficient indium tin oxide （ITO）-free inverted polymer solar cells （PSCs） were fabricated by applying ultrathin metal transparent electrodes as sunlight incident electrodes. Smooth and continuous Ag film of 4 nm thickness was developed through the introduction of a 2 nm Au seed layer. Ultrathin Ag transparent electrode with an average transmittance of up to 80% from 480 to 680 nm and a sheet resistance of 35.4Ω/sq was obtained through the introduction of a ZnO anti-reflective layer. The ultrathin metal electrode could be directly used as cathode in polymer solar cells without oxygen plasma treatment. ITO-free inverted PSCs obtained a power conversion efficiency （PCE） of 5.2% by utilizing the ultrathin metal transparent electrodes. These results demonstrated a simple method of fabricating ITO-free inverted PSCs.