(US5919951-A)      A method of preparing a thiophene-containing or furan-containing conjugated compound, involves heating a precursor compound comprising a unit having thermally separable substituents, to eliminate the separable substituents while converting the precursor compound into the thiophene- or furan-containing conjugated compound; the precursor unit used being a tetrahydrothiophene or tetrahydrofuran unit having thermally separable substituents (-SR1 and -SR2), in which R1 and R2 are alkyl or aryl groups.    Also claimed are: (1) soluble precursor compound comprising a precursor unit consisting of a tetrahydrothiophene or tetrahydrofuran unit having thermally separable substituents -SR1 and -Sr2, in which R1 and R2 are alkyl or aryl groups; and    (2) a semiconductor device having a layer comprising a polythiophene obtained using the above method.    USE -   The conjugated compounds prepared are useful in semiconductor devices, in dyes or pigments, electroluminescent material and in electrical, optical and electro-optical devices, such as light emitting diodes (LEDs), field effect transistors, solar cells, polarizing optical elements and batteries.    ADVANTAGE -   Low conductivity in combination with a high mobility constitute ideal electrical properties when using mixtures of thiophene polymers and oligomers.    (US6124475-A)      A method of preparing a thiophene-containing or furan-containing conjugated compound, involves heating a precursor compound comprising a unit having thermally separable substituents, to eliminate the separable substituents while converting the precursor compound into the thiophene- or furan-containing conjugated compound; the precursor unit used being a tetrahydrothiophene or tetrahydrofuran unit having thermally separable substituents (-SR1 and -SR2), in which R1 and R2 are alkyl or aryl groups.    Also claimed are: (1) soluble precursor compound comprising a precursor unit consisting of a tetrahydrothiophene or tetrahydrofuran unit having thermally separable substituents -SR1 and -Sr2, in which R1 and R2 are alkyl or aryl groups; and    (2) a semiconductor device having a layer comprising a polythiophene obtained using the above method.    USE -   The conjugated compounds prepared are useful in semiconductor devices, in dyes or pigments, electroluminescent material and in electrical, optical and electro-optical devices, such as light emitting diodes (LEDs), field effect transistors, solar cells, polarizing optical elements and batteries.    ADVANTAGE -   Low conductivity in combination with a high mobility constitute ideal electrical properties when using mixtures of thiophene polymers and oligomers.    (US6184540-B1)      A method of preparing a thiophene-containing or furan-containing conjugated compound, involves heating a precursor compound comprising a unit having thermally separable substituents, to eliminate the separable substituents while converting the precursor compound into the thiophene- or furan-containing conjugated compound; the precursor unit used being a tetrahydrothiophene or tetrahydrofuran unit having thermally separable substituents (-SR1 and -SR2), in which R1 and R2 are alkyl or aryl groups.    Also claimed are: (1) soluble precursor compound comprising a precursor unit consisting of a tetrahydrothiophene or tetrahydrofuran unit having thermally separable substituents -SR1 and -Sr2, in which R1 and R2 are alkyl or aryl groups; and    (2) a semiconductor device having a layer comprising a polythiophene obtained using the above method.    USE -   The conjugated compounds prepared are useful in semiconductor devices, in dyes or pigments, electroluminescent material and in electrical, optical and electro-optical devices, such as light emitting diodes (LEDs), field effect transistors, solar cells, polarizing optical elements and batteries.    ADVANTAGE -   Low conductivity in combination with a high mobility constitute ideal electrical properties when using mixtures of thiophene polymers and oligomers.