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Prof. Chang Sun

Key Laboratory of Flexible Electronics (KLOFE), Institute of Advanced Materials (IAM), Nanjing Tech University

Co-Affiliations:Peking University

Research Publications & English Decoded Briefs

Showing 4 publications
SCIENCE CHINA Materials2026DOI: 10.1007/s40843-026-4279-0

Inkjet Printing Organic Light-Emitting Diodes

Inkjet printing has emerged as a viable additive manufacturing route for organic light-emitting diodes (OLEDs), offering drop-on-demand patterning, high material utilization, and compatibility with large-area flexible substrates. This review critically examines the formulation science, printhead physics, and drying kinetics that govern the quality of inkjet-printed organic layers. We analyze the rheological window required for stable jetting, typically 1–20 mPa·s viscosity and 25–45 mN/m surface tension, and the dimensionless Ohnesorge number (0.1 < Z < 1) that defines satellite-free droplet formation. The coffee-ring effect, driven by capillary flow and solvent evaporation gradients, remains the dominant failure mode for pixel non-uniformity; binary solvent systems and substrate temperature control (40–60 °C) mitigate this. We survey recent progress in printed hole-transport, emissive, and electron-transport layers, with particular attention to cross-linkable hole-transport materials that resist interlayer dissolution. Device performance metrics from printed OLEDs now reach external quantum efficiencies of 15–20% for fluorescent emitters and >25% for phosphorescent systems, with operating lifetimes (T95) exceeding 1,000 hours at 1,000 cd/m². We identify remaining bottlenecks: nozzle clogging from aggregated nanoparticles, film thickness variation across large panels, and the absence of standardized ink formulations. The review concludes with a roadmap for industrial adoption, emphasizing in-line metrology and closed-loop process control as prerequisites for yield parity with vacuum-deposited OLEDs.

The Chinese Journal of Process Engineering2026DOI: 10.12034/j.issn.1009-606X.226111

Hydrogen-bonded networks and N2O/N2 adsorption separation performance of pyridinecarboxylate guanidinium HOFs

Efficient capture of the greenhouse gas nitrous oxide (N2O) is critical for climate change mitigation and resource recovery. In this study, two guanidinium-based hydrogen-bonded organic frameworks (HOFs) with pyridyl nitrogen site isomerism, namely G-5,5'-BPyDC and G-4,4'-BPyDC, were constructed using 2,2'-bipyridine-5,5'-dicarboxylic acid and 2,2'-bipyridine-4,4'-dicarboxylic acid as ligands. The effects of ligand structure on hydrogen-bonded network, pore environment, and N2O/N2 adsorption separation performance were systematically investigated via single-crystal X-ray diffraction, thermogravimetric analysis, Hirshfeld surface analysis, and gas adsorption experiments. Both frameworks are built via N-H...O hydrogen bonds. The asymmetric unit of G-5,5'-BPyDC contains two methanol molecules, resulting in larger free volume and surface area compared to G-4,4'-BPyDC, which exhibits more compact packing. Both materials show decomposition temperatures above 290°C, indicating good thermal stability. Hirshfeld surface analysis reveals that the total contribution of O-H/H-O and N-H/H-N hydrogen bonds in G-5,5'-BPyDC (32.0%) is higher than that in G-4,4'-BPyDC (29.7%). At 25°C and 4.0 MPa, the N2O adsorption capacity of G-5,5'-BPyDC is 2.32 mmol/g, surpassing that of G-4,4'-BPyDC (2.02 mmol/g). IAST calculations show that the selectivities of G-5,5'-BPyDC for N2O/N2 (50:50 and 10:90) mixtures reach 29.26 and 111.32, respectively, significantly superior to those of G-4,4'-BPyDC (6.61 and 17.03). Pyridyl nitrogen site isomerism effectively optimizes N2O/N2 adsorption and separation by modulating pore polarity and hydrogen-bonded network, offering a new strategy for isomer design.

SCIENCE CHINA Materials2026DOI: 10.1007/s40843-025-3786-8

Dual-mode electrotunable near-infrared chiral organic synaptic photodiodes for intelligent cancer detection

Conventional cancer diagnostic techniques, such as tissue sampling and microscopy, are invasive and prone to misdiagnosis, driving the need for non-invasive, precise alternatives. Chiral biophotonics, exploiting circularly polarized light (CPL), offers unique polarization-selective interactions with biological tissues, enabling higher imaging contrast and molecular-level discrimination. However, current CPL detection technologies are passive and single-mode, lacking dynamic tunability and parallel processing capabilities. Meanwhile, AI-assisted diagnostics rely on separated sensing and computing units, suffering from poor integration and transmission inefficiency. Here, we report a near-infrared (NIR) chiral organic synaptic photodiode with electrically tunable dual-mode operation, enabling simultaneous CPL detection and neuromorphic processing. Under negative bias, the device operates as a highly sensitive CPL detector for chiroptical signal acquisition. Under positive bias, it exhibits history-dependent synaptic behavior with photocurrent dissymmetry factor (g_ph) dynamically tunable up to -0.06. By integrating this device into an optical convolutional neural network (OCNN), we achieved intelligent cancer detection with CPL-based imaging. Experimental results demonstrate that CPL detection accuracy reaches 83%, approaching the theoretical 87%, significantly outperforming natural light detection at 65%. The device enhances image contrast and feature extraction, laying a foundation for intelligent, adaptive diagnostic systems.

SCIENCE CHINA Materials2026DOI: 10.1007/s40843-025-3742-5

Function block combination in light-driven cholesteric liquid crystal elastomer actuator

Nematic liquid crystal elastomers (NLCEs) exhibit excellent mechanical properties and diverse deformation modes, while cholesteric liquid crystal elastomers (CLCEs) as photonic crystals (PCs) possess superior optical performance and intelligent response characteristics. Combining these two elastomers into a monolithic material is a challenging yet promising endeavor. Here, we designed and synthesized a new diselenide-bonded molecule (DSeAc), whose lower bond energy between selenium atoms endows it with excellent bond exchange ability. Consequently, two LCE matrices containing DSeAc molecules can achieve seamless bonding under mild conditions via dynamic diselenide bond exchange. By integrating a CLCE film and an NLCE actuator into a monolithic film, we enable the integration of two functional components, whose functional characteristics can be tailored as required. This function block combination strategy offers a promising pathway for developing smart materials with complex functions, showing great potential in information storage, anti-counterfeiting, and biomimetics.