Investigation of thermal control in phase-changing ABO 3 perovskites via first-principles predictions: general mechanism of solar absorptivity.

The fundamental mechanism of solar absorbance during the phase-change process is investigated in ABO 3 perovskites based on first-principles predictions. A Gaussian-like relationship between the solar absorbance and band gaps is established, which follows the Shockley-Queisser limiting efficiency. For ABO 3 perovskites with bandgaps of E g > 3.5 eV, a low solar absorbance is obtained, whereas a high solar absorbance is obtained for ABO 3 perovskites, with band gaps ranging from 0.25 to 2.2 eV. The relationship between the orbital character of the density of states (DOS) and the absorption spectra reveals that ABO 3 perovskites with magnetic (strongly interacting) and distorted crystal structures always exhibit a higher solar absorptivity. In contrast, non-magnetic and cubic ABO 3 perovskites always exhibit a lower solar absorptivity. Moreover, the tunable solar absorptivity always undergoes a phase change from cubic to large distorted crystal structures in ABO 3 perovskites with strong interactions. These results can be attributed to a rich structural, electronic, and magnetic phase diagram resulting from the strong interplay between the lattice, spin, and orbital degrees of freedom, which induce highly tunable optical characteristics in the phase-change process. The findings presented in this study are critical for the development of ABO 3 perovskite-based smart thermal control materials in the spacecraft field.