Bandgap energy tuning and photoelectrical properties of self-assembly quantum well structure in organic-inorganic hybrid perovskites

Organic-inorganic hybrid perovskite materials have excellent performance in optical, electrical and magnetic properties. The energy-band structure of the hybrid materials can be tuned at the molecular level. In this paper, thin films of hybrid perovskite (C6H13NH3)2(CH3NH3)n-1PbnI3n+1 (n=1, 2, 3, n is the number of two-dimensional inorganic-sheet) have been successfully prepared by a simple spin-coating method. The effects of the inorganic-sheet number (n) on the crystal structure, bandgap energy, exciton binding energy, photoluminescent emission and photocondunctive performance of the hybrid materials have been investigated systematically. With the increasing of inorganic-sheet number, the exciton absorption peak shows an obvious red shift, the bandgap becomes narrow, and the exciton binding energy decreases. Further, the exciton is separated into holes and electrons easily due to the expansion of the exciton Bohr radius and, moreover, the carrier mobilities are increased due to the increasing of inorganic-layer thickness. Consequently, the photocondunctivity of the films is greatly enhanced.