Current cutting-edge theoretical descriptions of solid-state devices (solar PV cells and their partners, light-emitting diodes, field-effect transistors, diode

Current cutting-edge theoretical descriptions of solid-state devices (solar PV cells and their partners, light-emitting diodes, field-effect transistors, diode lasers, etc. all seem to involve applications of the complicated density functional theory, a replacement for earlier many-nuclei, many-electron wave function approaches (which were computationally intractable). It's a very complex linear-algebra-heavy theory, but anyone interested in this field will eventually end up having to grasp it. One could philosophize as to whether the resulting theoretical picture is closer to reality than the previous approach, but ultimately these are just models, and comparison of predictions with experimental results is the real test. For an introduction: (2014) "Density Functional Theory in the Solid State", Hasnip et al. https://sci-hub.se/10.1098/rsta.2013.0270 https://sci-hub.se/10.1098/rsta.2013.0270 See section 4, "Semiconductor physics/device technologies": > "DFT simulations are increasingly important in the field of device technologies, and used to study everything from conventional CMOS devices to future devices based on half-metals, thermoelectrics or multiferroics. Obtaining the correct band-gap for the constituent (doped/defect) materials is essential to describe the functionality of these devices." Since transistor sizes have now reached the so-called quantum limit, the electron tunneling phenomenon is now a limiting issue, requiring new materials and DFT-based electronic structure prediction. P.S. Wikipedia has a good article on field-effect transistors: https://en.wikipedia.org/wiki/Field-effect_transistor https://en.wikipedia.org/wiki/Field-effect_transistor