Hasan Mammad Bagir oglu Abdullayev (born 20.08.1918) is a Soviet physicist, an academician of the Academy of Sciences of the Azerbaijan SSR (1967) and its president (since 1970), and a corresponding member of the USSR Academy of Sciences (1970). He was born in the village of Yaydzhi. He graduated from the Azerbaijan Pedagogical Institute (1941). Since 1950 he has worked at the Institute of Physics of the Academy of Sciences of the Azerbaijan SSR (from 1954 as its director), and he is also professor at Azerbaijan University.His research concerned semiconductor physics and biophysics. In his work on the physics of selenium and on selenium devices he was the first to explain the anomalous phenomena in selenium and to indicate ways of controlling its properties. He carried out a large body of work on growing single-crystal semiconductors of complex chemical composition for lasers and memory elements. Abdullayev's studies of the physical properties of new complex semiconductors led to the creation of controllable diodes with an electrical memory. He developed new semiconductor materials for thermal converters.