Negative Differential Resistance Electronics: From Nonmonotonic Transport Physics to Functionally Compressed Computing

Negative differential resistance (NDR), a counterintuitive transport phenomenon in which current decreases with increasing voltage, challenges conventional transistor‐centric computing paradigms based on monotonic electronic transport and opens new opportunities for beyond‐Boolean computing. Here, we present a comprehensive and concept‐driven review of NDR devices spanning memristor‐based, diode‐type, and transistor‐based platforms. We establish a unified framework that links diverse NDR mechanisms, including resonant tunneling, electrothermal feedback, defect dynamics, and ferroelectric polarization, through their shared nonmonotonic transport characteristics. Beyond device‐level classification, we further propose NDR as a physical foundation for functionally compressed computing, in which circuit functionalities traditionally implemented using multiple transistors and feedback networks can be partially embedded into the intrinsic nonlinear response of a single NDR device or compact device unit. We further compare representative NDR technologies using common performance metrics and analyze the key challenges that currently limit large‐scale deployment, including variability, CMOS compatibility, compact modeling, and the distinction between intrinsic NDR behavior and measurement‐induced artifacts. Finally, we discuss future opportunities in materials‐by‐design, heterogeneous and 3D integration, physics‐informed modeling, and closed‐loop intelligent systems. By connecting nonmonotonic transport physics with circuit and system‐level functionality, NDR electronics offers a promising route toward compact and energy‐efficient computing architectures in the post‐Moore era.