Charge transfer properties in P3HT:graphene capped InAs/GaAs QDs hybrid heterostructure for photovoltaic application

In this work we have developed hybrid organic/inorganic nanostructure based on InAs/GaAs quantum dots (QDs) capped with P3HT:graphene organic nanocomposite using spin-coating method. InAs/GaAs QDs are grown by molecular beam epitaxy on n+-GaAs (0 0 1) substrate. The morphological properties are studied through atomic force microscopy (AFM) and scanning tunneling microscopy (STM). Raman spectroscopy analyzes show that the encapsulation of the InAs/GaAs QDs by P3HT:graphene nanocomposite keeps unchanged the indium concentration in the quantum dots due to the negligible strain effect of the organic cap layer on the QDs compared with the conventional GaAs cap layer. The quenching of the photoluminescence (PL) intensity of P3HT proves that an electrons transfer process from P3HT to graphene and from P3HT to InAs/GaAs QDs has occurred. We show that the proposed P3HT:graphene cap layer could replace the conventional GaAs cap layer for the elaboration of optoelectronic devices.