Collaborative Research: Understanding Defect Passivation, Charge Injection, and Degradation in Ultra-Bright Halide Perovskite LEDs and Lasers

About This Grant

Highly efficient and low-cost light emitting diodes (LEDs) are critical for the future energy landscape in the United States. They are widely used in displays and lighting. Current technologies use high temperature and high vacuum for materials processing and device fabrication, which are energy- and infrastructure-demanding. In this project, LED devices based on a new type of semiconductors—the so-called organic-inorganic hybrid perovskites—will be studied. These materials exhibit excellent optical and optoelectronic properties required for LED applications. In addition, they can be processed at low temperature under mild conditions, making the device fabrication and integration much easier. This research will enable future LED devices that are efficient, scalable and cost-effective. This project will also provide interdisciplinary training to undergraduate and graduate students, providing them with critical-thinking and problem-solving skills needed for future careers in areas of semiconductor technology. Halide perovskites are an exciting family of materials with excellent optical and electronic properties, particularly promising as next-generation light sources. However, a significant scientific gap exists in understanding the defect activities and degradation pathways associated with their reactive surfaces and mixed ionic-electronic transport. The goal of this project is to directly address these questions via design of novel materials and 2D/3D heterostructures that are less reactive and lead to reduced defect density, suppressed ion migration, and enhanced stability. Particularly, this project aims to demonstrate extremely bright and stable perovskite LEDs (PeLEDs) that can operate at application-relevant and high current density over 1000 mA/cm2 with over 200 hours lifetime. Based on such devices, the team will also explore the possibility of electrically driven lasing via nanosecond pulsed excitation exceeding 10 kA/cm2, unlocking a range of applications with a non-epitaxial laser diode. Three specific objectives are: 1) Materials design and interface engineering toward efficient, stable, and color-tunable halide perovskite LEDs; 2) Elucidation of materials and device degradation mechanisms via multi-modal characterization; 3) Evaluation of device behavior at extremely high injection current densities toward electrically driven lasing. The proposed approaches of interfacial engineering and fundamental understanding of degradation pathways systematically address instability issues caused by surface reactions which release ions that then trigger other issues. This will lead to a breakthrough toward long-term stability in perovskite-LEDs. Moreover, this new materials and device platform will allow researchers to explore the possibility of electrically driven lasing – a long-lasting challenge in non-epitaxial semiconductor devices. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.