solar cells, and organic light emitting diodes. Because their perovskite precursors are commercially available, the study of PSCs has recently become an important emerging scientific field. [1] Today, the critical issues for PSC development are related to increasing their performance and stability. [2] Because the short-circuit current densities (J sc ) of PSC devices have almost approached their theoretical limit, efforts directed toward further increasing the performance have been based on increasing their open-circuit voltages (V oc ) and fill factors (FFs). Such approaches will necessitate optimizing the morphology, the interfacial layers, the device architectures, and the hole/electron transporting layers. [3] With advances in device engineering and materials, the power conversion efficiencies (PCEs) of PSCs have skyrocketed from 3.8% to 22.7% within the last six years. [1e,f,3c,4] Efforts at optimizing the morphologies of PSC films (i.e., their grain size, coverage, and crystallinity) have directly led to greater PSC performance. For example, variations in the solvents, thermal engineering techniques, and additives have all played roles in improving the quality of the resulting perovskite films. [5] Many types of additives-including metal/organic halide salts, solvents, Lewis bases, [6] inorganic acids, polymers, [7] and fullerenes-can enhance the morphologies and efficiencies of PSCs. [8] Considering the complexity of perovskite formation, the vast array of fabrication parameters, and the myriad materials that can be involved in the process, there remains plenty of room for new discoveries in this field.Because perovskite films are generally prepared through solution processes, the presence of defects-ones that cause nonradiative energy loss and decrease the values of V oc and efficiencies-is unavoidable. Tuning the composition to passivate the defects of perovskites (using such materials as pyridine [9] and polymers [8a] ) can be an efficient means of improving the performance of PSCs. In this present study, we employed carbon nanodots (CNDs) as additives that efficiently tailor the optoelectronic properties of perovskites. Because of their nanoscale dimensions, tunable optoelectronic properties, and ready synthesis (to present various functional groups), the study of CNDs has experienced rapid development, especially for Carbonized bamboo-derived carbon nanodots (CNDs) as efficient additives for application in perovskite solar cells (PSCs) are reported. These carboxylic acid-and hydroxyl-rich CNDs interact with the perovskite through hydrogen bonds and, thereby, promote the carriers' lifetimes and realize high-performance p-i-n PSCs having the structure indium tin oxide/ NiO x /CH 3 NH 3 PbI 3 (MAPbI 3 )/PC 61 BM/BCP/Ag. As a result of interactions between the CNDs and the perovskite, the presence of the nonvolatile CND additive increases the power conversion efficiency (PCE) of the PSC from 14.48% ± 0.39% to 16.47% ± 0.26%. Furthermore, adding urea, a Lewis base, increases the PCE to 20.2%-the re...
Improved high-yield synthesis of N-aryl azetidine-2,4-dione has been achieved. The azetidine-2,4-dione undergoes ring-opening reactions with aliphatic primary amines to form malonamide linkages. More importantly, this compound exhibits a high reactivity toward primary aliphatic amine group over alcohols or secondary amines. This selective end-group functionalization is useful for preparing useful polymer intermediates. In this study polymalonamides were synthesized by fast addition reaction of aliphatic diamine and azetidine-2,4-dione. In the meantime, further application for structure-controlled reaction also has been demonstrated.
In this study, we used direct molecular exfoliation for the rapid, facile, large-scale fabrication of single-layered graphene oxide nanosheets (GOSs). Using macromolecular polyaniline (PANI) as a layered space enlarger, we readily and rapidly synthesized individual GOSs at room temperature through the in situ polymerization of aniline on the 2D GOS platform. The chemically modified GOS platelets formed unique 2D-layered GOS/PANI hybrids, with the PANI nanorods embedded between the GO interlayers and extended over the GO surface. X-ray diffraction revealed that intergallery expansion occurred in the GO basal spacing after the PANI nanorods had anchored and grown onto the surface of the GO layer. Transparent folding GOSs were, therefore, observed in transmission electron microscopy images. GOS/PANI nanohybrids possessing high conductivities and large work functions have the potential for application as electrode materials in optoelectronic devices. Our dispersion/exfoliation methodology is a facile means of preparing individual GOS platelets with high throughput, potentially expanding the applicability of nanographene oxide materials.
A series of novel dendrons serving as surfactants for surface modification of montmorillonite (MMT) have been synthesised via a convergent approach. The most distinguishing characteristic of the prepared dendrons is the long alkyl chain at the periphery. This would certainly bring about good solubility, high yield and easy purification. By simple acidification of the "head group'' upon the dendron and then ion-exchange with Na+-MMT, the interlayer distance could be enlarged significantly between the layered silicates. The organic/inorganic ratio determined by thermogravimetric analysis (TGA) is in the range of 60% - 91%. This also confirms the occurrence of dendron ion-exchange with Na+-MMT. Transmission electronic microscopy (TEM) reveals the intercalated and exfoliated morphology of the dendron-modified MMTs. Modification using the generation 2 dendritic surfactant (G2) with molecular weight (M-w) = 2887.5 has achieved the exfoliated morphology in this work
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