Dual-Functional ITO Interlayer for Effective Defect Passivation and Cationic Composition Engineering in Kesterite...

Area of Science:

• Materials Science
• Renewable Energy
• Semiconductor Physics

Background:

• Copper Zinc Tin Sulfoselenide (CZTSSe) solar cells face performance limitations due to back interface interdiffusion and absorber defects.
• These issues hinder the efficiency and stability of CZTSSe photovoltaic devices.

Purpose of the Study:

• To address limitations in CZTSSe solar cells by introducing an Indium Tin Oxide (ITO) interlayer.
• To investigate the dual-functional role of ITO as a diffusion barrier and a source of Sn and In during selenization.
• To optimize CZTSSe absorber layer composition and reduce defect density.

Main Methods:

• Introduction of an ITO interlayer at the back interface of CZTSSe solar cells.
• Analysis of ITO's function as a diffusion barrier during the initial selenization stage.
• Observation of ITO's role as a self-sacrificing layer supplying Sn and In in later selenization stages.
• Characterization of defect reduction and elemental composition redistribution within the absorber layer.

Main Results:

• The ITO interlayer effectively suppressed elemental migration, preventing loss towards the Mo electrode.
• ITO acted as a source for Sn and In, reducing Sn-related vacancy and substitutional defects.
• Reverse saturation current density decreased significantly from 4.14 × 10^-7 to 2.67 × 10^-8 A/cm², indicating reduced carrier recombination.
• The optimized ITO-10 sample achieved a photoelectric conversion efficiency of 13.11%.

Conclusions:

• The ITO interlayer demonstrates a synergistic mechanism for defect regulation and bulk doping in CZTSSe solar cells.
• This approach significantly enhances the performance of CZTSSe solar cells by mitigating key limitations.
• ITO presents a promising interlayer material for advancing CZTSSe solar cell technology.