The Structural, stability, electronic and optoelectronics properties of Y2AgBiX6 (Y = K, Na, li; X = I, Br, Cl) halide double Perovskites: A First-Principles study

The crystal structure, electronic and optoelectronic properties of halide double perovskites Y2AgBiX6 (Y = K, Na, Li; X = I, Br, Cl) have been studied by first principles (FPs) in this paper. According to the elastic modulus and formation energy of crystal Li2AgBiX6, its structural stability is poor. In addition, the dependence of their electronic and mechanical properties, the effective mass of carriers and light absorption on elemental compo-sition has been analyzed, and it is inferred that these materials have good electron transport properties. The photovoltaic characteristics of halide perovskite materials (PMs) based on potassium and sodium are studied. The photovoltaic properties of perovskite films with thickness of 1 & mu;m, 5 & mu;m and 10 & mu;m were further analyzed, and it was found that the absorption was the highest when the film thickness was 10 & mu;m. The current-voltage curve of the solar cell with above perovskite as absorbing material is calculated and analyzed by first principles. The result shows that Na2AgBiBr6, Na2AgBiCl6, K2AgBiI6 and K2AgBiCl6 are predicted to have excellent photovoltaic properties. Compared to other commonly used PMs, perovskite Y2AgBiX6 (Y = K, Na, Li; X = I, Br, Cl) has a smaller effective mass, which may contribute to good carrier transport and high performance of its optoelectronic devices. The absorption curves of K2AgBiBr6, K2AgBiCl6, Na2AgBiBr6, Li2AgBiBr6, and Li2AgBiCl6 matched well with the spectral irradiance of AM 1.5. Taken together, K2AgBiBr6 and Na2AgBiBr6 are the most suitable can-didates for solar cell absorption layers because of their appropriate band gap and good stability.