He collaborated on projects with physicists, computer scientists and electronic and electrical engineers. His interest in the toxicity of metal ions led to collaborations and publications with toxicologists, pharmacists and clinicians.[10] He was an advocate of communicating science to a wider audience and gave popular talks – usually on nanotechnology – including Café Scientifique and school lectures. He edited several books, including a series on nanotechnology for the Royal Society of Chemistry (RSC).[10]
O'Brien was passionate about international development and over two decades he worked tirelessly to encourage excellence in teaching and learning across Africa, with very strong ties to the University of Zululand.[12] His efforts changed the lives of many young African scientists and his students called him their “Father of Chemistry”.[13]
Paul O'Brien is distinguished for his many original contributions to chemistry and materials science, notably in the use of novel molecularly defined precursors from which to prepare important functional electronic or optical materials in well-defined forms. Processes he pioneered have been widely adopted. His discoveries include substantial improvements in the constitution, stoichiometry and nature of precursors. He has shown how relatively stable compounds can be used to prepare high quality functional materials, and developed improved methods to convert precursors into useful functional products, devising and refining ways by which nanoparticles syntheses can be controlled within the size limits require for device use[14]
^O'Brien, Paul (1978). Catalysis of the racemization of amino acids (PhD thesis). University of Wales. OCLC896125568. ProQuest301320104. (subscription required)
^Trindade, Tito; O'Brien, Paul; Pickett, Nigel L. (2001). "Nanocrystalline Semiconductors: Synthesis, Properties, and Perspectives". Chemistry of Materials. 13 (11): 3843–3858. doi:10.1021/cm000843p. hdl:10773/5962. ISSN0897-4756.
^Govender, Kuveshni; Boyle, David S.; Kenway, Peter B.; O'Brien, Paul (2004). "Understanding the factors that govern the deposition and morphology of thin films of ZnO from aqueous solution". J. Mater. Chem. 14 (16): 2575–2591. doi:10.1039/B404784B. ISSN0959-9428.
^Trindade, Tito; O'Brien, Paul; Zhang, Xiao-mei (1997). "Synthesis of CdS and CdSe Nanocrystallites Using a Novel Single-Molecule Precursors Approach". Chemistry of Materials. 9 (2): 523–530. doi:10.1021/cm960363r. hdl:10773/5787. ISSN0897-4756.