1,3,5-Triazine-Based Microporous Polymers with Tunable Porosities for CO₂ Capture and Fluorescent Sensing

The synthetic control over pore structure remains highly desirable for porous organic frameworks. Here, we present a competitive chemistry strategy, i.e., a systematical regulation on Friedel–Crafts reaction and Scholl coupling reaction through tuning the ratios of monomers. This leads to a series of spirobifluorene-based microporous polymers (Sbf-TMPs) with systematically tuned porosities and N content. Unlike the existing copolymerization strategy by which the synthesized polymers exhibit a monotonic change tendency in the porosities, our networks demonstrate an unusually different trend where the porosity increases first and then decreases with the increasing Ph/Cl ratios for the monomers. This is mainly ascribed to the completion of coexisting reaction routines and the different “internal molecular free volumes” of the repeating units. The as-made networks feature tunable capacities for CO₂ adsorption over a wide range and attractive CO₂/N₂ selectivities. Moreover, these donor–acceptor type frameworks exhibit selective and highly sensitive fluorescence-on or fluorescence-off properties toward volatile organic compounds, which implies their great potential in fluorescent sensors

Highly Flexible Self-Powered Organolead Trihalide Perovskite Photodetectors with Gold Nanowire Networks as Transparent Electrodes

Organolead trihalide perovskites (OTPs) such as CH₃NH₃PbI₃ (MAPbI₃) have attracted much attention as the absorbing layer in solar cells and photodetectors (PDs). Flexible OTP devices have also been developed. Transparent electrodes (TEs) with higher conductivity, stability, and flexibility are necessary to improve the performance and flexibility of flexible OTP devices. In this work, patterned Au nanowire (AuNW) networks with high conductivity and stability are prepared and used as TEs in self-powered flexible MAPbI₃ PDs. These flexible PDs show peak external quantum efficiency and responsivity of 60% and 321 mA/W, which are comparable to those of MAPbI₃ PDs based on ITO TEs. The linear dynamic range and response time of the AuNW-based flexible PDs reach ∼84 dB and ∼4 μs, respectively. Moreover, they show higher flexibility than ITO-based devices, around 90%, and 60% of the initial photocurrent can be retained for the AuNW-based flexible PDs when bent to radii of 2.5 and 1.5 mm. This work suggests a high-performance, highly flexible, and stable TE for OTP flexible devices

Direct Conversion of Perovskite Thin Films into Nanowires with Kinetic Control for Flexible Optoelectronic Devices

With significant progress in the past decade, semiconductor nanowires have demonstrated unique features compared to their thin film counterparts, such as enhanced light absorption, mechanical integrity and reduced therma conductivity, etc. However, technologies of semiconductor thin film still serve as foundations of several major industries, such as electronics, displays, energy, etc. A direct path to convert thin film to nanowires can build a bridge between these two and therefore facilitate the large-scale applications of nanowires. Here, we demonstrate that methylammonium lead iodide (CH₃NH₃PbI₃) nanowires can be synthesized directly from perovskite film by a scalable conversion process. In addition, with fine kinetic control, morphologies, and diameters of these nanowires can be well-controlled. Based on these perovskite nanowires with excellent optical trapping and mechanical properties, flexible photodetectors with good sensitivity are demonstrated