Excitonic bands in the spectra of some organic-inorganic hybrid compounds based on metal halide units

The optical absorption, photoluminescence, and photoconductivity spectra of some compounds of the formulas [R(CH2)(n)NH3](x)MyXz, [R(CH2)(n)NH(CH3)(2) ](x)MyXz, [R(CH2)(n)S(CH3)(2)](x)MyXz, [R(CH2)(n)SC(NH2)(2)](x)MyXz, and [R (CH2)(n)SeC(NH2)(2)](x)MyXz (R = organic residue; M = Bi(III), Pb(II), Sn(I I), Cu(I), Ag(I) etc; X = I, Br, Cl; n, x, y, z = 0, 1, 2, 3,...) are brief ly reviewed, and some new results are reported. The position, intensity, an d shape of the excitonic bands depend on the dimensionality and size of the inorganic network as well as on the nature of the M, X, R, and onium moiet ies.