Naughty Paul

More-efficient charge collection and suppressed trap recombination in colloidal quantum dot (CQD) solar cells is achieved by means of a bulk nano-heterojunction (BNH) structure, in which p-type and n-type materials are blended on the nanometer scale. The improved performance of the BNH devices, compared with that of bilayer devices, is displayed in higher photocurrents and higher open-circuit voltages (resulting from a trap passivation mechanism).

The absorbing layer in state-of-the-art colloidal quantum-dot solar cells is fabricated using a tedious layer-by-layer process repeated ten times. It is now shown that methanol, a common exchange solvent, is the main culprit, as extended exposure leaches off the surface halide passivant, creating carrier trap states. Use of a high-dipole-moment aprotic solvent eliminates this problem and is shown to produce state-of-the-art devices in far fewer steps.

Flowerlike MoS₂ microspheres were synthesized through a hydrothermal method. 2H-MoS₂ nanoparticles, MoS₂/MoO₃ heterojunctions, and α-MoO₃ nanoplates were prepared by annealing the MoS₂ microspheres under different reaction conditions. The formation and growth mechanism of the samples from flowerlike MoS₂ microspheres to α-MoO₃ nanoplates is explained in detail. The photocatalytic properties of the four samples for the degradation of rhodamine B (RhB) under visible-light irradiation were studied. The results showed that the flowerlike MoS₂ microspheres, MoS₂/α-MoO₃ heterojunctions, and α-MoO₃ nanoplates all have excellent photocatalytic activities. In particular, the flowerlike MoS₂ microspheres exhibit the highest photocatalytic activity for the degradation of RhB.

Flowerlike MoS₂ microspheres are used as a precursor for the preparation of 2H-MoS₂ nanoparticles, MoS₂/α-MoO₃ heterojunctions, and α-MoO₃ nanoplates. The growth mechanism is studied in detail. Among the four samples, the MoS₂/α-MoO₃ heterojunctions and MoS₂ microspheres show excellent photocatalytic activity.

A quantum-dot (QD) p-i-n heterojunction solar cell with an increased depletion region is demonstrated by depleting the QD layer from both the front and back junctions. Due to a combination of improved charged extraction and increased light absorption, a 120% increase in the short-circuit current is achieved compared with that of conventional ZnO/QD devices.

Primary alkyl amines (RNH₂) have been empirically used to engineer various colloidal semiconductor nanocrystals (NCs). Here, we present a general mechanism in which the amine acts as a hydrogen/proton donor in the precursor conversion to nanocrystals at low temperature, which was assisted by the presence of a secondary phosphine. Our findings introduce the strategy of using a secondary phosphine together with a primary amine as new routes to prepare high-quality NCs at low reaction temperatures but with high particle yields and reproducibility and thus, potentially, low production costs.

Identifying roles: ³¹P NMR and absorption spectroscopy was used in conjunction with DFT calculations to identify the reaction pathways leading to semiconductor nanocrystals (NCs), together with compounds 1–4 (see scheme). With SePPh₂H as the Se precursor instead of SeP(C₈H₁₇)₃, the conversion takes place at low temperature. The amine contributes to the formation of the two nitrogen compounds 1 and 2.

A symbiosis of advanced scanning probe and electron microscopy and a well-defined model system may provide a detailed picture of interfaces on nanostructured catalytic systems. This was demonstrated for Pt nanoparticles supported on iron oxide thin films which undergo encapsulation by supporting oxide as a result of strong metal–support interactions.

A symbiosis of advanced scanning probe and electron microscopy and a well-defined model system may provide a detailed picture of interfaces on nanostructured catalytic systems. This was demonstrated for Pt nanoparticles supported on iron oxide thin films, which undergo encapsulation by supporting oxide as a result of strong metal–support interactions (see picture).

Alloying in monolayers enables bandgap tuning in twodimensions. On page 2648, L. Xie, J. Zhang, and co-workers demonstrate that by direct evaporation of two end materials (MoS₂ and MoSe₂) and deposition at low temperatures, large-area 2D MoS_2(1−x)Se_2x monolayers are obtained. By changing the S/Se composition, the bandgap of MoS_2(1−x)Se_2x monolayers can be continuously tuned.