In order to produce energy efficient devices, thorough understanding of fundamental desired and undesired processes of energy and heat interconversion and migration are needed. I will present studies using time-resolved optical methods such as absorption and emission as functions of sample temperature and photon energy that aim to arrive at insights regarding energy transfer, electron transfer, and electron-phonon and phonon-phonon scattering events. Materials examined include nanoscale colloidal quantum wells and bulk-phase perovskites.