Xiaojun Wei

Compared with the single surfactants adopted in earlier studies, mixed surfactants exhibit superior capabilities in terms of chirality recognition and separation of single-wall carbon nanotubes (SWCNTs) because of their unique synergistic interactions in various liquid-phase separation methods. In this study, we designed diverse combinations of multiple surfactants and comprehensively investigated their chirality selectivity. The results of systematic separation experiments based on gel chromatography demonstrated a novel ternary-surfactant system, which has not been reported thus far but possesses significantly higher selectivity for both the diameter and chiral angle of SWCNTs than other combinations do. Through precise concentration modulation of ternary surfactants for controlling the chirality-selective adsorption and desorption of SWCNTs on a gel medium, we successfully separated near-zigzag single-chirality SWCNTs with ultrahigh and near-perfect optical chirality purity (∼100%), thereby reaching the highest level reported to date. Furthermore, the results of spectroscopic titration experiments and first-principle calculations revealed that the higher chirality selectivity originates from the much higher affinity of the present ternary-surfactant system for near-zigzag SWCNTs than for near-armchair SWCNTs, providing a greater understanding of the molecular interactions between surfactants and SWCNTs. Our findings address the issue of the greater difficulty in producing small-chiral angle SWCNTs and facilitate their applications in single-photon sources, optoelectronic devices, and bioimaging.

Flexible perovskite solar cells (FPSCs) have fired widespread research enthusiasm due to their great potential in the booming field of flexible electronics and portable devices. A lot of research has been conducted on the performance, flexibility, and stability of FPSCs, but the synergistic improvement between them is still terribly difficult. In this work, we have achieved the lightweight and ultra-flexible perovskite solar cell (LWUF PSC) with high performance and remarkable stability. Specifically, in addition to using a 1.5 µm-thick polyetherimide film as flexible substrate, the improved scheme mainly includes designing a "sandwich" architecture with multifunctionality to take advantage of perovskite quantum dots and polycrystalline perovskite, employing a flexible electrode of graphene-carbon nanotube film, and a hole transport layer of CuCrO₂ nanoparticles containing nickel to facilitate the transfer of photogenerated charge carriers. The resultant device demonstrates a stable power conversion efficiency (PCE) of 17.4% and a power-per-weight of 31.1 W g^-1. In particular, after 10,000 bending cycles with a curvature radius of 1 mm, the PCE of the LWUF PSC has sustained at 92.8% of its initial level, and after 32 days in an atmosphere with a relative humidity of 35%, it has remained at 93.0% of its initial level. The unique device’s structure design gives the LWUF PSC high PCE, significant power-per-weight, excellent mechanical flexibility and outstanding environmental stability – one of the best performance to date of LWUF PSCs without indium tin oxide electrodes.

The chiral self‐assembly of achiral molecules has sparked significant interest because of its capacity to transcend the intrinsic properties of achiral monomers while eliciting emergent chiral characteristics and applications. Herein, the study presents a systematic investigation of achiral tetraphenyl porphyrin (TPP) self‐assembly utilizing chirality‐sorted achiral (10,0) single‐wall carbon nanotubes (SWCNTs) as structuring templates. Comprehensive characterization through optical absorption and photoluminescence spectroscopies confirms the effective stacking of non‐water‐soluble TPP molecules onto nanotube surfaces within surfactant‐stabilized aqueous media, achieved through optimized ultrasonication and centrifugation processes. Notably, a robust bisignate circular dichroism signal is detected for the stacked TPPs, providing definitive spectroscopic evidence of the chiral self‐assembly of inherently achiral TPP molecules into optically active helical architectures on SWCNT templates. Furthermore, the current chiral self‐assembly of TPP molecules driven by strong π–stacking interactions with SWCNTs is further verified to exhibit reversible thermodynamic behaviour, which can be precisely manipulated through the TPP/SWCNT concentration ratio and environmental temperature. The findings establish a versatile platform consisting of 1D SWCNT templates for inducing and manipulating chirality in achiral molecular systems and provide fundamental insights critical for advancing chiral recognition/sensing technologies and enantioselective catalysis applications.

Shear-force feedback-based scanning near-field optical microscopy (SNOM) has emerged as a vital technique for optical characterization at the nanoscale. However, the low energy conversion efficiency of the aperture fiber tip (ATFT) limits their applications in nanospectroscopy. To overcome these challenges, the plasmonic fiber tip (PFT) was integrated into shear-force feedback-based SNOM, thereby establishing the tip-enhanced Raman spectroscopy (TERS) platform. With the fiber radial vector mode (RVM) internally exciting the PFT, the resultant tip nanofocusing light source exhibits a significant enhancement in both the electric-field intensity and the electric-field gradient effect, simultaneously. This advance ensures the resolution of the shear-force topography while obtaining the nanospectral information on the analytes, such as the gradient-field Raman spectrum. The developed fiber-RVM internal excitation-based SNOM-TERS platform holds significant promise for applications in nanophotonics and other fields that require precise spectral characterization at the nanoscale.

High‐efficiency extraction of long single‐wall carbon nanotubes (SWCNTs) with excellent optoelectronic properties from SWCNT solution is critical for enabling their application in high‐performance optoelectronic devices. Here, a straightforward and high‐efficiency method is reported for length separation of SWCNTs by modulating the concentrations of binary surfactants. The results demonstrate that long SWCNTs can spontaneously precipitate for binary‐surfactant but not for single‐surfactant systems. This effect is attributed to the formation of compound micelles by binary surfactants that squeeze the free space of long SWCNTs due to their large excluded volumes. With this technique, it can readily separate near‐pure long (≥500 nm in length, 99% in content) and short (≤500 nm in length, 98% in content) SWCNTs with separation efficiencies of 26% and 64%, respectively, exhibiting markedly greater length resolution and separation efficiency than those of previously reported methods. Thin‐film transistors fabricated from extracted semiconducting SWCNTs with lengths >500 nm exhibit significantly improved electrical properties, including a 10.5‐fold on‐state current and 14.7‐fold mobility, compared with those with lengths <500 nm. The present length separation technique is perfectly compatible with various surfactant‐based methods for structure separations of SWCNTs and is significant for fabrication of high‐performance electronic and optoelectronic devices.

High-purity enantiomer separation of chiral single-wall carbon nanotubes (SWCNTs) remains a challenge compared with electrical type and chirality separations due to the limited selectivities for both chirality and handedness, which is important for an exploration of their properties and practical applications. Here, we performed length fractionation for enantiomer-purified SWCNTs and found a phenomenon in which the enantioselectivities were higher for longer nanotubes than for shorter nanotubes due to length-dependent interactions with the gel medium, which provided an effective strategy of controlling nanotube length for high-purity enantiomer separation. Furthermore, we employed a gentler pulsed ultrasonication instead of traditional vigorous ultrasonication for preparation of a low-defect long SWCNT dispersion and achieved the enantiomer separation of single-chirality (6,5) SWCNTs with an ultrahigh enantiomeric purity of up to 98%, which was determined by using the linear relationship between the normalized circular dichroism intensity and the enantiomeric purity. Compared with all results reported previously, the present enantiomeric purity was significantly higher and reached the highest level reported to date. Due to the ultrahigh selectivity in both chirality and handedness, the two obtained enantiomers exhibited perfect symmetry in their circular dichroism spectra, which offers standardization for characterizations and evaluations of SWCNT enantiomers.

Although individual carbon nanotubes (CNTs) are superior to polymer chains, the mechanical and thermal properties of CNT fibers (CNTFs) remain inferior to synthetic fibers because of the failure of embedding CNTs effectively in superstructures. Conventional techniques resulted in a mild improvement of target properties while degrading others. Here, a double-drawing technique is developed to rearrange the constituent CNTs. Consequently, the mechanical and thermal properties of the resulting CNTFs can simultaneously reach their highest performances with specific strength ~3.30 N tex ⁻¹ (4.60 GPa), work of rupture ~70 J g ⁻¹ , and thermal conductivity ~354 W m ⁻¹ K ⁻¹ despite starting from low-crystallinity materials ( I _G : I _D ~ 5). The processed CNTFs are more versatile than comparable carbon fiber, Zylon and Dyneema. On the basis of evidence of load transfer efficiency on individual CNTs measured with in situ stretching Raman, we find that the main contributors to property enhancements are the increasing of the effective tube contribution.