2016/09/26 by Aniket Singha, Singha, Aniket, Bhaskaran Muralidharan +1
Materials Science · Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Advanced Thermoelectric Materials and Devices #FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Quantum and electron transport phenomena
paper · pdf · doi:10.48550/arxiv.1609.07894
openalex publication_date 2016/09/26 · openalex created_date 2022/10/03 · openalex updated_date 2026/07/28
The physics of energy filtering in electronic transport through nanoscale\nbarriers is a fundamental aspect in the context of electronic engineering of\nnanostructured thermoelectrics. In the context of thermoelectric generators, it\naims to engineer the Seebeck coefficient to favorably increase the power factor\nand ultimately the power generated. In this work, we employ the incoherent\nnon-equilibrium Green's function formalism to investigate in detail the physics\nof energy filtering and how it leads to a direct enhancement in power\ngeneration across nanostructured thermoelectrics featuring a single planar\nenergy barrier. In particular, we reinforce that the enhancement in the\ngenerated power via energy filtering at a particular operating efficiency is a\ncharacteristic of incoherent scattering and is absent in ballistic devices. In\nsuch cases, by assuming an energy dependent relaxation time, \τ(E)=kEr, we\nshow that there exists a minimum value rmin for which the thermoelectric\npower generation is enhanced and thereby leading to a degradation in power\ngeneration for r<rmin. For bulk generators, we delve into the details of\nintermode scattering and show that such scattering processes between electrons\nin higher energy modes and lower energy modes have a finite contribution to the\nenhancement in the generated power. We also discuss realistic aspects such as\nfinite width of energy barriers and imperfect energy filtering due to partial\nreflections. In particular, we show that such imperfect filtering and partial\ntransmission of electrons near the top of the barrier affects the enhancement\nin the generated power drastically in the high efficiency regime of operation.\nAnalysis of the results obtained in this work should provide general design\nguidelines for nanostructured enhancement in power generation via energy\nfiltering.\n