Challenges and strategies in developing high-performance n-type polycrystalline SnSe thermoelectric materials

This review comprehensively examines recent advances in n-type SnSe thermoelectric materials, addressing the critical performance gap with their p-type counterparts. We analyze the fundamental challenges imposed by intrinsic defect chemistry, anisotropic transport, and doping limitations that have historically constrained n-type SnSe development. The discussion systematically evaluates synthesis approaches spanning bulk crystal growth to nanostructured thin films, highlighting how processing conditions influence microstructural evolution and thermoelectric properties. A central focus is placed on doping strategies, including halogen-based and transition metal systems that enable carrier concentration optimization and phonon scattering enhancement. By synthesizing theoretical insights with experimental breakthroughs, this review identifies key knowledge gaps and proposes actionable research directions to realize high-performance n-type SnSe materials, ultimately enabling the development of efficient SnSe thermoelectric devices.