Some unconventional organic-inorganic hybrid low-dimensional semiconductors and related light-emitting devices

Structural, optical, electrical, and optoelectronic properties, as well as prototype light-emitting devices, are being reported for the two-dimensional (quantum well) organic-inorganic hybrid semiconductor systems based on the organic cations CH₃(CH₂)₇CH=CH(CH ₂)₈NH₃⁺ (OL) and on the inorganic networks formed out of MX₄^2- anions, where M = Pb and X = I, Br, and Cl. These new crystalline compounds show extremely intense excitonic bands at chemically controllable positions in the ultraviolet-visible spectral region, with excitonic binding energies of more than 180 meV at room temperature. These novel properties render them as strong potential candidates in optoelectronic applications, comparable to the artificial low-dimensional systems. Prototype light-emitting devices (LED) based on the above-mentioned compounds exhibit naked eye electroluminescence, in some cases, semicontinuous operation, for the first time at room temperature. In addition, these devices operate at relatively low voltages and are readily realized. Because of the enhanced film-forming and degradation-resistant properties of the active materials, the device functionality is being exhibited for weeks. Thus, it is expected that this particular reported synthetic route of hybrid organic-inorganic semiconductors could provide cost-effective materials for novel optoelectronic devices. Moreover, the properties of some composite systems of the type (CH₃NH₃)_n-1(OL)₂Pb _nX_3n+1 are being reported briefly.