Light emission from biased tunnel junctions has recently gained much attention owing to its unique potential to create ultracompact optical sources with terahertz modulation bandwidth^1,2,3,4,5. The emission originates from an inelastic electron tunnelling process in which electronic energy is transferred to surface plasmon polaritons and subsequently converted to radiation photons by an optical antenna. Because most of the electrons tunnel elastically, the emission efficiency is typically about 10⁻⁵–10⁻⁴. Here, we demonstrate efficient light generation from enhanced inelastic tunnelling using nanocrystals assembled into metal–insulator–metal junctions. The colour of the emitted light is determined by the optical antenna and thus can be tuned by the geometry of the junction structures. The efficiency of far-field free-space light generation reaches ~2%, showing an improvement of two orders of magnitude over previous work^3,4. This brings on-chip ultrafast and ultracompact light sources one step closer to reality.

偏置隧道结的发光由于其独特的潜力可以创建具有^1,2,3,4,5太赫兹调制带宽的超紧凑型光源而备受关注。发射源于非弹性电子隧穿过程，在该过程中，电子能量被转移到表面等离激元极化子，然后通过光学天线转换为辐射光子。由于大多数电子是弹性隧穿的，因此发射效率通常约为10 ^-5 –10 ^-4。在这里，我们演示了使用组装成金属-绝缘体-金属结的纳米晶体增强的非弹性隧穿产生的有效光。发射光的颜色由光学天线确定，因此可以通过结结构的几何形状进行调整。远场自由空间光的产生效率达到〜2％，比以前的工作^3,4提高了两个数量级。这使片上超快和超紧凑型光源离现实更加近了一步。