Quantum effects in nanoscale electronic devices promise to lead to new types of functionality not achievable using classical electronic components. However, quantum behaviour also presents an unresolved challenge facing electronics at the few-nanometre scale: resistive channels start leaking owing to quantum tunnelling. This affects the performance of nanoscale transistors, with direct source–drain tunnelling degrading switching ratios and subthreshold swings, and ultimately limiting operating frequency due to increased static power dissipation. The usual strategy to mitigate quantum effects has been to increase device complexity, but theory shows that if quantum effects can be exploited in molecular-scale electronics, this could provide a route to lower energy consumption and boost device performance. Here we demonstrate these effects experimentally, showing how the performance of molecular transistors is improved when the resistive channel contains two destructively interfering waves. We use a zinc-porphyrin coupled to graphene electrodes in a three-terminal transistor to demonstrate a >10⁴ conductance-switching ratio, a subthreshold swing at the thermionic limit, a >7 kHz operating frequency and stability over >10⁵ cycles. We fully map the anti-resonance interference features in conductance, reproduce the behaviour by density functional theory calculations and trace back the high performance to the coupling between molecular orbitals and graphene edge states. These results demonstrate how the quantum nature of electron transmission at the nanoscale can enhance, rather than degrade, device performance, and highlight directions for future development of miniaturized electronics.

纳米级电子设备中的量子效应有望带来使用传统电子元件无法实现的新型功能。然而，量子行为也提出了几纳米尺度电子学面临的一个尚未解决的挑战：由于量子隧道效应，电阻通道开始泄漏。这会影响纳米级晶体管的性能，直接源极-漏极隧道效应会降低开关比和亚阈值摆幅，并最终由于静态功耗增加而限制工作频率。减轻量子效应的通常策略是增加设备的复杂性，但理论表明，如果可以在分子级电子学中利用量子效应，这可以提供降低能耗和提高设备性能的途径。在这里，我们通过实验证明了这些效应，展示了当电阻沟道包含两个破坏性干扰波时分子晶体管的性能如何得到改善。我们在三端晶体管中使用与石墨烯电极耦合的锌卟啉来展示 >10 ^{4 的}电导切换比、热电子极限的亚阈值摆幅、>7 kHz 的工作频率以及 >10 ⁵周期的稳定性。我们完整地映射了电导中的反共振干扰特征，通过密度泛函理论计算重现了行为，并将高性能追溯到分子轨道和石墨烯边缘态之间的耦合。这些结果证明了纳米级电子传输的量子性质如何增强而不是降低器件性能，并突出了微型电子器件未来发展的方向。