Ag-Incorporated Organic-Inorganic Perovskite Films and Planar Heterojunction Solar Cells.

Abstract

Controlled doping for adjustable material polarity and charge carrier concentration is the basis of semiconductor materials and devices, and it is much more difficult to achieve in ionic semiconductors (e.g., ZnO and GaN) than in covalent semiconductors (e.g., Si and Ge), due to the high intrinsic defect density in ionic semiconductors. The organic-inorganic perovskite material, which is frenetically being researched for applications in solar cells and beyond, is also an ionic semiconductor. Here we present the Ag-incorporated organic-inorganic perovskite films and planar heterojunction solar cells. Partial substitution of Pb2+ by Ag+ leads to improved film morphology, crystallinity, and carrier dynamics as well as shifted Fermi level and reduced electron concentration. Consequently, in planar heterojunction photovoltaic devices with inverted stacking structure, Ag incorporation results in an enhancement of the power conversion efficiency from 16.0% to 18.4% in MAPbI3 based devices and from 11.2% to 15.4% in MAPbI3-xClx based devices. Our work implies that Ag incorporation is a feasible route to adjust carrier concentrations in solution-processed perovskite materials in spite of the high concentration of intrinsic defects.