As demand for high integration continues to grow, in‑situ integration of optoelectronic devices via thermal evaporation has gained increasing attention. This advantage has been demonstrated in organic light‑emitting diodes (OLEDs) and successfully commercialized. To maximize the benefits of thermal evaporation, it has been extended to emerging materials and devices such as perovskite LEDs (PeLEDs), perovskite solar cells (PSCs), and cluster LEDs (CLEDs). Unlike the purely physical vapor deposition of organic materials, the vapor‑phase preparation of these emerging materials involves complex processes including reactions, nucleation, and growth, each critically affecting film quality and requiring higher controllability and precision. This shift in vapor deposition mechanisms necessitates a re‑evaluation of the impact of the vapor‑phase atmosphere and the development of more precise gas purification techniques to maintain stable environmental conditions.
Conventional gas purification strategies typically rely on vacuum pumping using cascaded pumps. Despite their procedural simplicity, these methods exhibit significant limitations in impurity removal efficiency and capability ( Fig. 1a ). Moreover, prolonged vacuum pumping increases system complexity and extends the purification cycle.
Therefore, this paper proposes a novel one‑step vapor purification technique that successfully achieves a high‑purity vapor atmosphere with a total proportion of harmful gas-phase impurities below 1% ( Fig. 1b-d ). Using in‑situ residual gas analysis (RGA), the working mechanism and effective purification capability of this approach were verified, reducing the total gas-phase impurity content to below 1%. Benefiting from the purified vacuum chamber environment, the research team demonstrated the suppression of defect formation in thermally evaporated perovskite films under low‑impurity conditions, successfully achieving green thermally evaporated PeLEDs with an external quantum efficiency exceeding 20%. Furthermore, improvements in the operational and storage stability of integrated display panels indicate the commercial potential of this technology.
To verify its general applicability, the team also demonstrated the effectiveness of this strategy in OLEDs, achieving a significant extension in the operational lifetime of blue OLEDs. By addressing the vapor‑phase environment, this study provides in‑depth insights and key considerations regarding the atmosphere and gas‑phase reaction mechanisms in high‑performance optoelectronic devices. It is expected to further advance the development of high‑performance thermally evaporated optoelectronic devices and integrated systems, accelerating the practical application of technologies such as microdisplays and near‑eye displays.
Light Science & Applications
High-performance thermally-evaporated light-emitting diodes via one-step vapor purification