[The absorption spectra of crystal thin film Cs3Cu2I5]

In this paper we measured the absorption spectra of crystal thin film Cs3Cu2I5 at room and liquid nitrogen temperatures, respectively, and calculated the excitonic coefficient of the material. The excitonic coupling energy deltaE(ex)(1) = (0.53 +/- 0.07) eV, excitonic radius a(ex) = 0. 326 nm,and forbidden zone width E(g) = (5.00 +/- 0.07) eV. The spectral analysis shows that the electron and exciton excitations of the Cs3Cu2I5 localize in the CuI subcrystal lattice, and reveals the law that governs the variance of the first excitonic peak position of the serial Cs(x)Cu(1-x) I compounds with their mol-components at low temperature.