SKKU Researchers Develop Next-Generation Transparent Electrode Without Rare Metal Indium

- Nitrogen-doped SnO₂ (NTO) electrode overcomes  

limitations of conventional ITO, doubling device lifetime

- Paving the way for low-cost, high-efficiency commercialization of perovskite LEDs

A joint research team led by Professors Han-Ki Kim and Bo Ram Lee from the School of Advanced Materials Science and Engineering at SKKU has developed a next-generation transparent electrode technology that completely eliminates the use of the rare metal indium, while maintaining high performance and significantly extending device lifetime.

Perovskite light-emitting diodes (PeLEDs), which have recently attracted considerable attention as a key technology for next-generation displays, offer outstanding color purity and mechanical flexibility. However, conventional PeLEDs rely on indium tin oxide (ITO) as a transparent electrode. Indium, a rare and expensive metal, not only increases material costs but also suffers from a critical drawback: over time, indium ions can diffuse into the device, degrading performance and shortening operational lifetime.

▲Amrophous structure of Indium free N-doped Sno2

To address these limitations, the research team proposed a novel transparent electrode based on nitrogen-doped tin oxide (NTO), replacing indium with tin—an abundant and environmentally benign material. The NTO electrode was fabricated using a specialized nano-fabrication process, radio-frequency (RF) magnetron sputtering. Experimental results demonstrated that the NTO-based devices achieved a high external quantum efficiency (EQE) of 20.82%, comparable to that of conventional ITO-based devices.

Most notably, the study achieved a significant breakthrough in long-term stability. Devices incorporating the NTO electrode exhibited more than twice the operational lifetime compared to those using ITO electrodes. This improvement is attributed to the strong Sn–N bonding structure formed within the electrode, which effectively suppresses metal ion diffusion and acts as a robust barrier against degradation. In addition, the technology can be fabricated over large areas at relatively low temperatures, making it highly compatible with existing industrial manufacturing processes and advantageous for mass production.

▲ Next generation perovskite LED with Indium free N-doped SnO2 transparent electrodes

Professor Han-Ki Kim, who led the study, stated,“This work fundamentally addresses the limitations of conventional transparent electrode technologies that rely on expensive rare metals. It represents a major step toward sustainable, high-performance optoelectronic devices.”
He further added,“We expect this technology to accelerate the transition toward indium-free transparent electrodes, not only in display technologies but also in next-generation energy devices such as solar cells.”

This research was supported by the Ministry of Science and ICT under the “Next-Generation OLED Core Technology Development Program” and by the National Research Foundation of Korea. The findings were published online on February 26 in Materials Today(Impact Factor: 22.0), a leading international journal in materials science.

※ Title: Chemically durable and cost-efficient N-doped SnO2 transparent electrodes for Full-color perovskite light-emitting diodes

※ Journal: Materials Today (Impact Factor: 22.0)

※ DOI: https://doi.org/10.1016/j.mattod.2025.12.031