通過新穎材料及奈米結構設計開發具低閾值之室溫鈣鈦礦雷射元件
Exploiting Room-Temperature Perovskite Lasers with Low Thresholds through Advanced Materials and Nanostructure Engineering
國立臺灣大學化工系 闕居振 教授
中央研究院應科中心 呂宥蓉 副研究員
本合作計畫成功開發出可在室溫下穩定運作、具波長可調諧能力的單模準二維鈣鈦礦電漿子雷射元件。過去室溫奈米雷射的發展常受限於光學增益不足、材料不穩定及高雷射閾值等瓶頸。本團隊透過結合高品質準二維鈣鈦礦材料與高Q值電漿子表面晶格共振（SLR）腔，成功突破上述限制。
雙方貢獻與加乘性：
- 臺大團隊：專注於綠光準二維鈣鈦礦（Quasi-2D perovskite）增強發光層的開發與優化。透過「添加劑工程」在前驅物溶液中引入環狀分子 18-Crown-6，利用其與有機陽離子間的氫鍵作用調控結晶動力學，有效抑制低維度相（low-n phases）的隨機生成。此技術顯著改善薄膜形貌，將表面粗糙度7 nm降至3.9 nm，並大幅提升光致發光量子產率（PLQY）。更重要的是，藉由調整相分布建構高效能量傳遞階梯（Energy Funneling）並誘發「激子重定位效應」（Exciton Relocalization Effect），使載子能迅速集中至高 n 值相進行輻射複合，展現強烈的放大自發輻射（ASE），為低閾值室溫雷射提供穩定光學增益。
- 中研院團隊：主導電漿子共振腔的設計、奈米製程與光學特性鑑定。利用時域有限差分法（FDTD）開發波導混成表面晶格共振（W-SLR）系統，並精確優化鋁奈米顆粒（高度50 nm、直徑60 nm）的排列，形成高Q值腔體與強侷域電磁場。製程上，透過100-keV電子束微影技（EBL）在石英基板上製備週期介於275–375 nm的大面積鋁奈米結構陣列，實現波長調諧。此外，該團隊進一步以飛秒脈衝雷射與時間相關單光子計數系統（TCSPC）進行進階特性鑑定，證實元件具備超低雷射閾值（0.9 mJ/cm²）、高度線性偏振（偏振比0.88）、以及Purcell效應驅動的超快輻射複合（激子壽命由724 ps縮短至18 ps）。此外，元件在 1.8 × 106次脈衝激發下仍保持卓越穩定性。
- 合作加乘性：臺大團隊所開發的高增益、高穩定度鈣鈦礦薄膜，與中研院團隊設計的高效電漿子腔體深度互補。藉由SLR模式極大縮小光學模式體積並增強光物質交互作用（Purcell effect），有效彌補金屬結構能量損耗，徹底釋放準二維鈣鈦礦作為增益介質的潛力。此成果不僅在室溫大氣環境下實現超低閾值與長效運行，更為下一代光通訊與量子光學技術提供具規模化、低成本與高能源效率的奈米雷射平台。
This collaborative project successfully developed a single‑mode quasi‑2D perovskite plasmonic laser capable of stable operation and wavelength tuning at room temperature. Historically, the advancement of room‑temperature nanolasers has been hindered by insufficient optical gain, material instability, and high lasing thresholds. By integrating quasi‑2D perovskite materials with high‑Q plasmonic surface lattice resonance (SLR) cavities, the team overcame these long‑standing limitations.
Respective Contributions and Synergy:
- NTU Team: Focused on the development and optimization of the green quasi‑2D perovskite emission layer. Through advanced additive engineering, 18‑Crown‑6 was introduced into the precursor solution, leveraging strong hydrogen bonding with organic cations to regulate crystallization kinetics and suppress random stacking of low‑n phases. This approach resolved the non‑uniform morphology typical of quasi‑2D films, reducing surface roughness from 7 nm to 3.9 nm and yielding smooth, pinhole‑free films with markedly enhanced photoluminescence quantum yield (PLQY). Crucially, by tailoring phase distribution, the team established an efficient energy‑funneling ladder and induced an exciton relocalization effect, enabling rapid carrier transfer to high‑n phases for radiative recombination. The resulting amplified spontaneous emission (ASE) provided exceptionally high and stable optical gain, forming the essential basis for low‑threshold, room‑temperature lasing.
- Academia Sinica Team: Led the design of the plasmonic resonator, precision nanofabrication, and advanced optical characterization. Using finite‑difference time‑domain (FDTD) simulations, the team developed a waveguide‑hybridized SLR (W‑SLR) system. Optimized arrays of aluminum nanoparticles (50 nm height, 60 nm diameter) generated intense localized electromagnetic fields and high‑Q cavities. Fabrication employed 100‑keV electron beam lithography to produce large‑area arrays with periodicities of 275–375 nm on quartz substrates, enabling wavelength tunability. Characterization with femtosecond pulsed lasers and time‑correlated single‑photon counting (TCSPC) confirmed an ultra‑low lasing threshold (0.9 mJ/cm²), highly linear polarized emission (polarization ratio 0.88), and ultrafast radiative recombination driven by the Purcell effect, with exciton lifetimes shortened from 724 ps to 18 ps. The device further demonstrated outstanding stability under 1.8 × 106 excitation pulses.
- Synergy: The high‑gain, high‑stability perovskite films from NTU were seamlessly integrated with Academia Sinica’s efficient plasmonic resonators. The SLR mode drastically reduced optical mode volume and enhanced light–matter interaction, compensating for the intrinsic energy losses of metallic structures. This deep complementarity fully unlocked the potential of quasi‑2D perovskites as gain media, achieving ultra‑low thresholds and long‑term ambient operation. The outcome establishes a scalable, low‑cost, and energy‑efficient nanolaser platform poised to advance next‑generation optical communication and quantum photonic technologies.