Sharif Digital Repository

Hybrid nanoparticle comprising of nanosilica (NS) and nanodiamond (ND), denoted by ND@NS, was synthesized by a two-step chemistry route and then incorporated into styrene-butadiene rubber (SBR) at low concentrations up to 5 phr by a two-roll mill. Physical hybrids of NS and ND, i.e., ND&NS, with a weight ratio similar to chemical hybrid (80:20 for NS:ND), were also incorporated into SBR. Field emission scanning electron microscopy observations revealed very fine dispersion of nanoparticles in the case of physical hybrids (ND&NS). In contrast, agglomerations and aggregation of nanoparticles were evidenced for ND@NS. Tensile and dynamic mechanical analyses exhibited a higher reinforcing effect... 

The high mobility of charge carriers in graphene (G) together with the ease of processing and tunable optical properties of colloidal quantum dots (CQD) has provided high-performance hybrids for the next generation of phototransistors. In order to get a higher quality film of PbS QDs, understanding the effect of the ligand exchange method is critical. So, to improve the interdot electronic coupling, we propose a new conducting ligand to prepare a dense and self-assembled active layer of FAPbI3-PbS quantum dots on G/Si/SiO2substrates. Quantum dot (QD) nanocrystalline films were preparedviatwo different procedures: liquid phase ligand exchange (LPE) and solid phase ligand exchange (SPE). SPE... 

The α-FAPbI3 perovskite nanocrystals exhibit interesting optical properties, which make them attractive for versatile optoelectronic applications; however, the spontaneous phase transformation to the non-perovskite phase (δ-FAPbI3) in humid conditions requires a new strategy to improve the phase stability of the material. We employed 3-Aminopropyl triethoxysilane (APTES)-assisted reprecipitation and sol-gel methods at ambient temperature to prepare stable α-FAPbI3 nanocrystals embedded in a silica matrix. Transmission electron microscopy (TEM) and X-ray diffraction analysis determined that ultrafine perovskite nanocrystals (11.5 ± 3 nm) were uniformly distributed in a silica matrix.... 

The type of passivating ligands and the ligand exchange method influence the quality of lead sulfide quantum dot films. This imparts on the efficiency of optoelectronic devices. To get a compact arrangement of the nanocrystals in a thin film (⁓100 nm) via self-assembling, we used organic-inorganic perovskites with mixed halides for the solid-state exchange of oleic acid ligands on PbS QDs (⁓ 4 nm). Formamidinium lead halides FAPbIxBr3-x (x= 3,2,1,0) were used. X-ray spectroscopy shows that successful replacement of oleic acid with FA happens by short immersion of the films (2 min) in the solution. Transmission electron microscopy shows that nano-scale cracks, short-range ordering, and fusion... 

Metal halide perovskite nanoparticles have recently attracted immense interest for photodetectors due to their outstanding optical and electronic properties such as high carrier diffusion length, tunable band gap (light absorption range), and high photoluminescence (PL) efficiency. Although significant progress has been achieved in the development of perovskites, their stability is yet to be addressed. To improve the stability and quantum efficiency of FAPbI3 perovskite nanocrystals, we present a room temperature protocol to fabricate fully passivated and stable FAPbI3 nanocrystals via 2D growth in the presence of amine ligands and an excess amount of the organic cations. The crystallization... 

Phototransistors based on MAPbI3 perovskite nanocrystals (NCs) blended into P3HT were fabricated with different NCs:P3HT weight ratios. The high absorption coefficient and unique optical properties of the perovskite nanocrystals in the blended devices induce a faster response time and a more stable photoresponse, as compared with pure P3HT phototransistors. In addition, the ILIGHT/IDARK ratio of the optimized device with a 2:1 wt ratio of MAPbI3 NCs to P3HT reaches 123, which is 63% higher than in pure P3HT phototransistors. These phototransistors may find application as tunable photosensors, due to their ease of fabrication and sensitivity. © 2022 Elsevier B.V  

Solution-processed lead sulfide quantum dots (PbS QDs) are very attractive as NIR-active semiconductors for the fabrication of cost-efficient optoelectronic devices. To control the thin film carrier transport, as well as stability, surface passivation is of crucial importance. Here, we present the successful surface passivation of PbS QDs by the formamidinium lead iodide (FAPbI3) ligand. An effective procedure for the fabrication of FAPbI3-passivated PbS QDs through a binary-phase ligand exchange protocol in hexane and n-methylformamide is demonstrated. It is shown that this solution-processed ligand exchange drastically changes the photoluminescence intensity, exciton recombination...