Modulating Surface Morphology Related to Crystallization Speed of Perovskite Grain and Semiconductor Properties of Optical Absorber Layer under Controlled Doping of Potassium Ions for Solar Cells

Abstract

Perovskite thin films with excellent optical semiconductor and crystallization properties and superior surface morphology are normally considered to be vital to perovskite solar cells (PSCs). In this paper, we systematically survey the process of modulating surface morphology and optical semiconductor and crystallization properties of methylammonium lead iodide film by controlling doping of K+ for PSC prepared in air and propose the mechanism of large K+-doped perovskite grain formation related to crystallization speed. The increase in the crystallization speed leads to the production of large grains without localized-solvent-vapor (LSV) pores via moderate doping of K+, and the exorbitant crystallization speed induces super large grains with LSV pores via excessive doping of K+. Furthermore, the semiconductor properties (absorption band edge wavelength, PL emission peak wavelength, energy band gap) of perovskite film can be significantly tuned by controlled doping of K+. The investigation of the detailed process of modulating surface morphology and semiconductor properties of perovskite thin film by controlled doping of K+ may provide guidance and pave the way for superior component design of absorption materials for cost-efficient PSCs.

Keywords

• solar cell
• doping of K+
• surface morphology
• perovskite thin film
• crystallization speed
• semiconductor properties