The PhD dissertation covers light emission properties, shift current (SC) photovoltaic efficiencies, and band gap renormalization caused by doping in two-dimensional materials studied utilizing first-principles computational techniques. These techniques include density functional theory (DFT), GW, and the Bethe-Salpeter equation (BSE).

The light emission results are based on ab initio center-of-mass momentum resolved exciton calculations, as covered in paper A and B. Here, the exciton band structures, thermally averaged exciton radiative lifetimes, and angular emission profiles are obtained and discussed. Results are obtained for the four TMDs MoS2, WS2, MoSe2, and WSe2, as well as biased bilayer graphene. The bright excitons split into light- and particle-like bands, yielding unique fingerprints for the light emission properties.

Doping based band gap renormalization is based on results from paper C and previously unpublished results. The renormalization arises from electron-electron interactions, thus, to study these ab initio DFT+G0W0 quasiparticle band structure calculations are performed. Results are presented for antidot graphene, MoS2, and WSe2, with a jellium slab corresponding to the doping. Based on this, doping density resolved effective masses and band gaps are obtained and analyzed, with effective masses differing by and order of magnitude between n and p-type doping.

Finally, shift current photovoltaic efficiencies are calculated for 326 different 2D materials obtained from the material database C2DB as covered in paper D. Two device setups are considered, namely in-plane SCs in mono- and multilayer samples. Multilayer samples show great promise, while the monolayer efficiencies are found to be significantly lower. Out-of-plane SCs are briefly considered and found to be comparable to in-plane results. Finally, material selection parameters, such as an optimal band gap range and compounds, are discussed.