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The weak effects induced by lattice disorder on the optoelectronic properties of halide perovskites still remain elusive. Here Wu et al. confirm the indirect transition tail states in perovskite crystals which explain their low photoluminescence quantum yield, dual emission peaks and difficulties in realizing lasing.

The hot carriers in halide perovskite nanocrystals cool much slower than those in conventional semiconductor nanocrystals due to the phonon bottleneck. Here, Li et al. demonstrate enhanced multiple exciton generation with lower threshold in intermediate-confined perovskite nanocrystals based on this effect.

The small high-order multi-photon action cross-section of traditional biological imaging media presents a fundamental limitation for deep-tissue nonlinear optical imaging. Here the authors overcome this limitation by employing multidimensional core–shell perovskite nanocrystals.

Harvesting excess energy from above-band gap photons could lead to solar cells which exceed conventional efficiency limits. Liet al., study hot carrier cooling in hybrid perovskite materials with reduced dimensionality using transient absorption spectroscopy and demonstrate efficient hot-electron extraction in such systems.

The original version of this article incorrectly listed the present address of Bo Wu as ‘Present address: Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, Guangdong Province 510006, China’. This is the author’s primary affiliation. This has been corrected in both the PDF and HTML versions of the article.

Nature Communications 8: Article number: 14350 (2017); Published: 8 February 2017; Updated: 25 May 2017 The original version of this Article contained a typographical error in the first sentence of the abstract in which ‘Shockley-Queisser’ was incorrectly given as ‘Schottky-Queisser’. This has now been corrected in both the PDF and HTML versions of the Article.

Electrical properties of reduced graphene oxide (rGO) decorated with gold and silver nanoparticles were studied. Metal nanoparticles p-dope rGO through charge transfer which causes a potential drop at the metal nanoparticle–graphene interface. Probing by reactive gases showed that the nanoparticles provide interaction sites, inducing the sensitivity to H2S and improving the sensitivity to NO2. [ABSTRACT FROM AUTHOR]

This communication describes development of a top gate solution processable organic memory solution. Transistor memories (p-type and ambipolar) operating at voltages between 20 and 30 V with memory on–off ratios close to 103at programming speeds of 1 ms were fabricated on glass and flexible PET substrates. Successful retention of the stored state for 1 week is also demonstrated. [ABSTRACT FROM AUTHOR]

We present organic field-effect transistor (OFET) memories where in-situsynthesized gold (Au) nanoparticles in self-assembled polystyrene-block-poly-4-vinylpyridine (PS-b-P4VP) block copolymer nanodomains successfully functioned as charge storage elements. Both p-type (pentacene) and n-type (perfluorinated copper phthalocyanine) OFET based memories are reported, which have stable large charge capacity and programmable-erasable properties due to charge confinement in the embedded Au nanoparticles. Optical excitation has been utilized to demonstrate photogenerated minority carrier trapping in the Au nanoparticles for efficient erasing operations. The memory devices can hence be written and read electrically and erased optically, resulting in large memory windows (∼9–11 V), high on/off ratio between memory states (103–105) and long retention times (>1000 s). The results clearly indicate the utility of the block copolymer-nanoparticle approach for OFET based memories. [ABSTRACT FROM AUTHOR]

The control of image contrast is essential toward optimizing a contrast enhancement procedure in optical coherence tomography (OCT). In this study, the in vivocontrol of optical contrast in a mouse tumor model with gold nanoshells as a contrast agent is examined. Gold nanoshells are administered into mice, with the injected dosage and particle surface parameters varied and its concentration in the tumor under each condition is determined using a noninvasive theoretical OCT modeling technique. The results show that too high a concentration of gold nanoshells in the tumor only enhances the OCT signal near the tissue surface, while significantly attenuating the signal deeper into the tissue. With an appropriate dosage, IV delivery of gold nanoshells allows a moderate concentration of 6.2×109 particlesmlin tumor to achieve a good OCT signal enhancement with minimal signal attenuation with depth. An increase in the IV dosage of gold nanoshells reveals a corresponding nonlinear increase in their tumor concentration, as well as a nonlinear reduction in the fractional concentration of injected gold nanoshells. Furthermore, this fractional concentration is improved with the use of antiepodermal growth factor receptor (EGFR) surface functionalization, which also reduces the time required for tumor delivery from 6 to 2 h. [ABSTRACT FROM AUTHOR]

The use of microfluidics for biofluid analysis offers a cheaper alternative to conventional techniques in disease diagnosis. However, traditional microfluidics design may be complicated by the need to incorporate separation elements into the system in order to facilitate specific molecular detection. Alternatively, an optical technique known as surface-enhanced Raman spectroscopy (SERS) may be used to enable identification of analyte molecules directly from a complex sample. This will not only simplify design but also reduce overall cost. The concept of SERS-based microfluidics is however not new and has been demonstrated previously by mixing SERS-active metal nanoparticles with a model sample, in situ, within the microchannel. Although the SERS reproducibility of these systems was shown to be acceptable, it is, however, not stable toward variations in the salt content of the sample, as will be shown in this study. We have proposed a microfluidics design whereby periodic SERS-active metal nanostructures are fabricated directly into the microchannel via a simple method of spin coating. Using artificial as well as human urine samples, we show that the current microfluidics is more stable toward variations in the sample’s ionic strength. [ABSTRACT FROM AUTHOR]