In modern energy conversion and solid-state thermoelectric physics, formulating materials that achieve Phonon-Glass Electron-Crystal (PGEC) behavior represents a core objective for maximizing the dimensionless thermoelectric figure of merit ($ZT$). An ideal thermoelectric material requires low lattice thermal conductivity (acting as a phonon glass) combined with high electrical conductivity and Seebeck coefficient (behaving as an electronic crystal). However, in conventional dense bulk solids, electronic and thermal transport are strongly coupled by the Wiedemann-Franz law. Semiconductor aerogels—characterized by three-dimensional nanoporous networks—provide a physical platform for decoupling phonon and electronic transport channels.

The solid backbones of semiconductor aerogels (such as bismuth sulfide, bismuth telluride, or zinc oxide nanoporous networks) consist of interconnected quantum dots or one-dimensional nanowires measuring only a few nanometers in diameter. Within these confined spaces, quantum confinement effects emerge. Because electron wavefunction coherence lengths become comparable to nanoscale structural dimensions, the electronic Density of States (DOS) undergoes reconstruction, exhibiting sharp van Hove singularities that enhance the Seebeck coefficient while maintaining electrical conductivity.

Concurrently, the internal network of crystal grain boundaries, pore interfaces, and interparticle neck junctions scatters thermal phonons. Phonon mean free paths are truncated at these nanoscale interfaces, suppressing lattice thermal conductivity to near-minimum limits. By regulating nanocrystalline dimensions and carrier concentrations within semiconductor aerogels, physicists decouple charge carrier transport channels from thermal phonon scattering pathways.