First-principles exploration of the interface characteristic between CNT and inorganic lead-free perovskites CsSnX3 (X = Cl, Br, I)

The structural, electronic, and optical characteristics of the CNT/CsSnX3 (X = Cl, Br, I) interfaces are investigated via first-principles calculations. All selected CNT/CsSnX3 interfaces remain stable in energy and their interfacial properties can be varied with the halogen anions changing from Cl to I. The calculated cohesive energy, interlayer distance as well as electron localization function indicate the CNT/CsSnX3 systems belong to vdW heterojunctions with weak interactions. Due to the large potential difference between CNT and CsSnX3, the internal electrostatic field formed at the interface, which reduces the probability of the electron–hole recombination effectively. The interfacial charges transfer from CsSnX3 to CNT when they contact. The absorption spectra of CNT/CsSnX3 contacts are higher than the corresponding CNT and CsSnX3, which could be attributed to the formation of interfacial contact. What's more, among all selected composites, CNT/CsSnI3 contacts with large charge transfers and minor structural changes should be the most appropriate configurations to get excellent photoelectric properties. These results exhibit interfacial properties of CNT/CsSnX3 from the atomic scale and provide theoretical guidance for developing novel perovskite devices.