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HighlightsThe introduction of hydroiodic acid (HI) manipulates the dynamic conversion of PbI2 into highly coordinated species to optimize the nucleation and growth kinetics.The addition of HI enables the fabrication of CsPbI3 perovskite quantum dots with reduced defect density, enhanced crystallinity, higher phase purity, and near-unity photoluminescence quantum yield.The efficiency of CsPbI3 perovskite quantum dot solar cells was enhanced from 14.07% to 15.72% together with enhanced storage stability.All-inorganic CsPbI3 quantum dots (QDs) have demonstrated promising potential in photovoltaic (PV) applications. However, these colloidal perovskites are vulnerable to the deterioration of surface trap states, leading to a degradation in efficiency and stability. To address these issues, a facile yet effective strategy of introducing hydroiodic acid (HI) into the synthesis procedure is established to achieve high-quality QDs and devices. Through an in-depth experimental analysis, the introduction of HI was found to convert PbI2 into highly coordinated [PbIm]2−m, enabling control of the nucleation numbers and growth kinetics. Combined optical and structural investigations illustrate that such a synthesis technique is beneficial for achieving enhanced crystallinity and a reduced density of crystallographic defects. Finally, the effect of HI is further reflected on the PV performance. The optimal device demonstrated a significantly improved power conversion efficiency of 15.72% along with enhanced storage stability. This technique illuminates a novel and simple methodology to regulate the formed species during synthesis, shedding light on further understanding solar cell performance, and aiding the design of future novel synthesis protocols for high-performance optoelectronic devices.

Photoluminescence (PL) mechanism of carbon quantum dots (CQDs) remains controversial up to now even though a lot of approaches have been made. In order to do that, herein a PL color ladder from blue to near infrared of CQDs with the absolute quantum yields higher than 70% were prepared via a one-pot hydrothermal synthesis route and separated by silica gel column. Time-correlated single photon counting measurements suggest that the electron transition takes in effect in the PL progress of the crystalline core-shell structured CQDs, and the PL properties could be coarsely adjusted by tuning the size of the crystalline carbon core owing to quantum confinement effects, and finely adjusted by changing the surface functional groups consisted shell owing to surface trap states, respectively. Both coarse and fine adjustments of PL, as optical and photoelectrical characterizations and density-functional theory (DFT) calculations have demonstrated, make it possible for top-level design and precise synthesis of new CQDs with specific optical properties.

Temperature and wavelength dependence of energy transfer (ET) process between quantized states and surface trap states of CdSe quantum dots was investigated, respectively. The experimental results demonstrate that the photoluminescence (PL) intensity of the quantized states decreases with respect to the trap state emission, especially at lower temperatures. The observed ET process between quantized states and trap states which is influenced by the thermal population behavior. At the same temperature, the silver films can greatly enhance the energy transfer (ET) rate from the quantized states to trap states due to surface plasmonic coupling effect.

The presence of surface trap states (STSs) is one of the key factors to affect the electronic and optical properties of quantum dots (QDs), however, the exact mechanism of how STSs influence QDs remains unclear. Herein, we demonstrated the impact of STSs on electron transfer in CdSe QDs and triplet-triplet energy transfer (TTET) from CdSe to surface acceptor using femtosecond transient absorption spectroscopy. Three types of colloidal CdSe QDs, each containing various degrees of STSs as evidenced by photoluminescence and X-ray photoelectron spectroscopy, were employed. Time-resolved emission and transient absorption spectra revealed that STSs can suppress band-edge emission effectively, resulting in a remarkable decrease in the lifetime of photoelectrons in QDs from 17.1 ns to 4.9 ns. Moreover, the investigation of TTET process revealed that STSs can suppress the generation of triplet exciton and effectively inhibit band-edge emission, leading to a significant decrease in TTET from CdSe QDs to the surface acceptor. This work presented evidence for STSs influence in shaping the optoelectronic properties of QDs, making it a valuable point of reference for understanding and manipulating STSs in diverse QDs-based optoelectronic applications involving electron and energy transfer.

Space charges tend to accumulate on the surface and at the interface of ethylene–propylene–diene terpolymer (EPDM), serving as high voltage direct current (HVDC) cable accessory insulation, which likely induces electrical field distortion and dielectric breakdown. Direct fluorination is an effective method to modify the surface characteristics of the EPDM without altering the bulk properties too much. In this paper, the surface morphology, hydrophobic properties, relative permittivity, and DC conductivity of the EPDM before and after fluorination treatment were tested. Furthermore, the surface and interface charge behaviors in the HVDC cable accessory were investigated by the pulsed electroacoustic (PEA) method, and explained from the point of view of trap distribution. The results show that fluorination helps the EPDM polymer obtain lower surface energy and relative permittivity, which is beneficial to the interface match in composite insulation systems. The lowest degree of space charge accumulation occurs in EPDM with 30 min of fluorination. After analyzing the results of the 3D potentials and the density of states (DOS) behaviors in EPDM before and after fluorination, it can be found that fluorination treatment introduces shallower electron traps, and the special electrostatic potential after fluorination can significantly suppress the space charge accumulation at the interface in the HVDC cable accessory.

Studies on the vertical distribution of arthropods in temperate forests have revealed the uneven vertical distribution of communities. Many factors influence these patterns simultaneously. However, there are still many questions related to the vertical distribution of Coleoptera in deciduous forests of the temperate zone. The research was carried out within the territory of the Republic of Mordovia (the center of the European part of Russia). Fermental traps with a bait made of fermenting beer with sugar were used to collect Coleoptera. The collections were carried out from May to September 2020 at five sites in a deciduous forest. We set traps at a height of 1.5, 3.5, 7.5 and 12 m above the ground) on the branches of trees. Ninety-two species were identified at the end of studies at different heights. The families Nitidulidae (15 species), Cerambycidae (14 species), Elateridae (7 species), Curculionidae (7 species) and Scarabaeidae (7 species) had the greatest species diversity. The greatest species diversity was recorded at a height of 1.5 m, while the smallest one was recorded at a height of 7.5 m. The minimum number of specimens was recorded at a height of 12 m. The largest differences in the Jaccard similarity index were obtained between samples from a height of 1.5 and 12 m. The Shannon’s diversity index was higher near the ground than in the tree crowns (at heights of 7.5 and 12 m), and the Simpson index had the opposite tendency. Glischrochilus hortensis and to a lesser extent Cychramus luteus preferred to live in the lowest layers of deciduous forest (1.5 m). Cryptarcha strigata was mainly found with relatively high numbers at heights of 3.5 m and 7.5 m. The abundance and occurrence of Protaetia marmorata and Quedius dilatatus were higher in the uppermost layers of the crowns. The number of saproxylic beetle species at heights of 3.5–12 m was almost the same, while in the surface layer it decreased. The number of anthophilic beetle species was also lower at a low altitude. Our data confirm the relevance of sampling in forest ecosystems at different altitudes while studying arthropod biodiversity.

Accurate surface tension measurements are key to understanding and predicting the behavior of atmospheric aerosols, particularly their formation, growth, and phase transitions. In Earth’s atmosphere, aerosols often exist in metastable states, such as being supercooled or supersaturated. Standard tensiometry instruments face challenges in accessing these states due to the large sample volumes they require and rapid phase changes near surfaces. We present an instrument that uses a strong electric field, nearing the dielectric strength of air, to deform aerosol microdroplets and measure surface tension in a contact-free, humidity-controlled environment. A dual-beam optical trap holds single microdroplets between two electrodes and excites Raman scattering. When a high voltage is applied, droplet deformations reach tens of nanometers. These small shape changes are precisely measured through the splitting of morphology-dependent resonances, seen as sharp peaks in Raman spectra. Our measurements cover water activities where droplets are supersaturated, a region with limited previous data, and show good agreement with existing data where comparisons are possible. Unlike prior levitation-based methods, this approach measures surface tension in systems with viscosities over 10 2  Pa s without relying on dynamic processes. Atmospheric aerosols are often in metastable states. Here, the authors present a non-contact method for measuring the surface tension in single microdroplets using electrodeformation and Raman scattering, which enables precise measurement of such states.

Silicon nanostructures have been prepared on Si wafer using electrochemical etching process. The transformation of aluminum/nanostructured Si junction from Schottky to Ohmic nature has been observed by varying the annealing temperature. This phenomenon has been explained by the temperature dependent shifting of energy levels of defects states instrumental in trapping charges within the forbidden band gap of Si nanostructures. The Aluminum (Al)/nano-Si junction shows asymmetric nature at room temperature and then changes to ohmic at moderate annealing temperature. Finally, at high temperature the junction becomes rectifying in nature. This transition has been explained on the basis of Fermi level pinning due to the modification of distribution of the non-stoichiometric silicon oxide related defect states present at the nanocrystalline Si core-oxide shell interface.

The manipulation of trap states plays a crucial role in the development of efficient photocatalysts. An ultrathin-shelled Zn-AgIn5S8/ZnS quantum dots (QDs) photocatalyst was synthesized via in situ growth using a low-temperature hydrothermal method. The optical properties of the samples coated with ZnS shell were studied vis UV-vis absorption and fluorescence spectra. The ultrathin ZnS shell plays an important role in the Zn-AgIn5S8/ZnS core–shell heterostructure photocatalytic water splitting system, which could reduce surface defects, prolong the carrier lifetime and improve the photo-generated electron–hole pair separation effectively, resulting in the improved photocatalytic efficiency and enhanced stability of the catalyst. The results provide an effective guideline for shell thickness design in future constructions of the core–shell heterostructure photocatalyst.

The electrical and physical properties of the SiC/SiO2 interfaces are critical for the reliability and performance of SiC-based MOSFETs. Optimizing the oxidation and post-oxidation processes is the most promising method of improving oxide quality, channel mobility, and thus the series resistance of the MOSFET. In this work, we analyze the effects of the POCl3 annealing and NO annealing processes on the electrical properties of metal–oxide–semiconductor (MOS) devices formed on 4H-SiC (0001). It is shown that combined annealing processes can result in both low interface trap density (Dit), which is crucial for oxide application in SiC power electronics, and high dielectric breakdown voltage comparable with those obtained via thermal oxidation in pure O2. Comparative results of non-annealed, NO-annealed, and POCl3-annealed oxide–semiconductor structures are shown. POCl3 annealing reduces the interface state density more effectively than the well-established NO annealing processes. The result of 2 × 1011 cm−2 for the interface trap density was attained for a sequence of the two-step annealing process in POCl3 and next in NO atmospheres. The obtained values Dit are comparable to the best results for the SiO2/4H-SiC structures recognized in the literature, while the dielectric critical field was measured at a level ≥9 MVcm−1 with low leakage currents at high fields. Dielectrics, which were developed in this study, have been used to fabricate the 4H-SiC MOSFET transistors successfully.