Research Projects

Rationale: Micro-LEDs (µ-LEDs) are the foundation of next-generation display technologies. The high-performance, low-cost, energy-efficient, premium display features make them suitable for use in television, monitors, AR/VR realities, and transparent and flexible displays. High PPI (pixels per inch) is important because it directly affects how sharp and clear the screen appears to the human eye. It is recommended that the PPI should be more than 2000 for high-quality displays. In this context, metal halide perovskite nanocrystals (PNCs) have emerged as a promising class of materials for lighting applications due to their intrinsically defect-tolerant nature, easy color tunability, and higher color purity than other lighting sources. Within a decade, the external quantum efficiency (EQE) of perovskite LEDs (PLEDs) reached more than 25%. PNCs exhibit ns-range recombination lifetimes, which are advantageous for high-refresh-rate displays. Their solution-processable nature offers compatibility with low-cost, large-area, and potentially scalable patterning techniques. The fabrication of PLEDs requires fewer layers and simpler interfaces than OLEDs and QLEDs. It is feasible to fabricate patterned PLED devices with a very high PPI density and flexible devices. On the other hand, the rapid expansion of global markets and information technology has stirred a significant increase in demand for anticounterfeiting technologies. The patterned PNC films can be engineered to emit specific colors or respond to particular wavelengths, temperatures, or other parameters, making them ideal for covert markings, QR codes, or authentication labels. This project aims to bridge the performance gap between state-of-the-art PNC technologies and practical display and security applications. The objectives of our proposal include: i) Synthesis of color-tunable stable PNCs with photoluminescent quantum yield (PLQY) close to unity; ii) growth of patterned color-tunable PNC films deposited via lithography techniques with pixel size down to 2 μm × 2 μm; iii) development of high-performance µ-LEDs with external quantum efficiency (EQE) close to 15% and luminance (L)~ 20000 Cd/m²; iv) demonstration of multimodal anticounterfeiting measures; v) Integration of these functional elements into mechanically flexible devices, enabling applications in wearable and transparent device technology. Hypothesis: The exciton binding energy of PNCs is comparatively higher than bulk films, which results in better charge-carrier confinement and improves the device stability. We hypothesize that patterned PNC films with optimized surface passivation, ligand engineering, and pixel isolation can enable stable and efficient RGB LEDs with improved resolution and brightness. The multimodal emission behaviour of these materials—particularly when doped or composited—can be leveraged to engineer anticounterfeiting signatures that are easy to authenticate while being difficult to replicate. Testing this hypothesis will involve detailed material-device correlation studies, degradation analysis, simulations, and device-level demonstrations. Main Experiments: Synthesis and ligand engineering of red, green, and blue-emitting PNCs with high photoluminescent quantum yield and enhanced stability; Lithographic patterning of RGB pixels on transparent and flexible substrates, with precise alignment and pixel isolation down to 2 μm resolution; Design and characterization of micro-LED devices, including EQE, luminance, stability, and spectral purity measurements; Design of multimodal anticounterfeiting features; Flexibility test. Significance: This project will deliver one of India’s first-of-its-kind demonstrations of color-tunable µ-PLEDs and their deployment in flexible and secure devices. The outcomes will advance the fundamental understanding and provide a new material platform alternative for µ-LED technologies. This project is strongly aligned with India's Atmanirbhar ambitions.