Regulation of Two-Dimensional Platelet Micelles with Tunable Core Composition Distribution via Coassembly Seeded Growth Approach.

Seeded growth termed "living" crystallization-driven self-assembly (CDSA) has been identified as a powerful method to create one- or two-dimensional nanoparticles. Epitaxial crystallization is usually regarded as the growth mechanism for the formation of uniform micelles. From this perspective, the unimer depositing rate is largely related to the crystallization temperature, which is a key factor to determine the crystallization rate and regulate the core composition distribution among nanoparticles. In the present work, the coassembly of two distinct crystallizable polymers is explored in detail in a one-pot seeded growth protocol. Results have shown that polylactone containing a larger number of methylene groups (-CH2-) in their repeating units such as poly(η-octalactone) (POL) has a faster crystallization rate compared to poly(ε-caprolactone) (PCL) with a smaller number of -CH2- at ambient temperature (25 °C), thus a block or blocky platelet structure with heterogeneous composition distribution is formed. In contrast, when the crystallization temperature decreases to 4 °C, the difference of crystallization rate between both cores become negligible. Consequently, a completely random component distribution within 2D platelets is observed. Moreover, we also reveal that the core component of seed micelles is also paramount for the coassembly seeded growth, and a unique structure of flower-like platelet micelle is created from the coassembly of PCL/POL using POL core-forming seeds. This study on the formation of platelet micelles by one-pot seeded growth using two crystallizable components offers a considerable scope for the design of 2D polymer nanomaterials with a controlled core component distribution.

Enhanced Photodetection Performance of Photodetectors Based on Indium-Doped Tin Disulfide Few Layers.

Two dimensional (2D) tin disulfide (SnS2) has attracted growing interest as a promising high performance photodetector with superior performance such as fast response time, high responsivity, and good stability. However, SnS2-based photodetectors still face great challenges, and the photodetection performance needs to be improved for practical applications. Herein, indium-doped SnS2 (In-SnS2) few layers were exfoliated from CVT-grown single crystals, which were synthesized by chemical vapor transport. Photodetectors based on In-SnS2 few layers were fabricated and detected. Compared with photodetectors based on pristine SnS2, photodetectors based on In-SnS2 few layers exhibited better photodetection performances, including higher responsivities, higher external quantum efficiencies, and greater normalized detectivities. The responsivity (R), external quantum efficiency (EQE), and normalized detectivity (D*) were increased by up to 2 orders of magnitude after In doping. Considering responsivity and response time, the photodetector based on 1.4 at. % In-SnS2 few layers exhibited an optimal photodetection performance with a high R of 153.8 A/W, a high EQE of 4.72 × 104 %, a great D* of 5.81 × 1012 Jones, and a short response time of 13 ms. Our work provides an efficient path to enhance photodetection performances of photodetectors based on SnS2 for future high-performance optoelectronic applications.