STRUCTURE AND COMPOSITION OF THIN-FILMS OF PERIPHERALLY UNSUBSTITUTED PHTHALOCYANINE DEPOSITED USING THE LANGMUIR-BLODGETT TECHNIQUE

Langmuir-Blodgett films of peripherally unsubstituted phthalocyanine (Pc) have been deposited on substrates of silicon, aluminized silicon and gallium arsenide by means of a precursor compound, dilithium phthalocyanine (Li2Pc), from an aqueous subphase. The resulting films have been chemically and structurally characterized using surface IR reflection spectroscopy, Raman spectroscopy, and secondary ion mass spectrometry. The results show that the films contain both Li2Pc and metal-free phthalocyanine, indicating that hydrolysis of Li2Pc by the aqueous subphase is not complete, contrary to previous assumptions in the literature. The resulting films are brittle and polycrystalline in nature, with little or no preferred molecular orientation. This behavior is thought to be due to the molecular association of the Li2Pc both in the spreading solution and on the aqueous subphase.