Enhancing Grain Growth for Efficient Solution-Processed (Cu,Ag)₂ZnSn(S,Se)₄ Solar Cells Based on Acetate Precursor

Area of Science:

• Materials Science
• Photovoltaics
• Semiconductor Physics

Background:

• Material crystallinity is crucial for photovoltaic device performance.
• Bilayer/trilayer structures in Cu2ZnSn(S,Se)4 (CZTSSe) absorbers increase carrier recombination at grain boundaries, hindering efficiency.

Purpose of the Study:

• To investigate the effect of anion application on (Cu,Ag)2ZnSn(S,Se)4 (CAZTSSe) materials.
• To improve grain size and crystallinity in CAZTSSe absorbers for enhanced photovoltaic performance.

Main Methods:

• Utilized acetate starting materials for precursor solution to form uniform, compact, and pinhole-free CAZTS precursor films.
• Employed selenization to enhance CAZTSSe film crystallization, achieving large grains throughout the absorber layer.

Main Results:

• Acetate route yielded improved film smoothness compared to the oxide route.
• Enhanced crystallization led to significantly reduced carrier recombination loss at grain boundaries.
• Open-circuit voltage (Voc) improved due to reduced recombination.

Conclusions:

• The application of anions, specifically via acetate precursors, effectively tunes the crystallization of CAZTSSe films.
• This approach successfully increased the power conversion efficiency (PCE) of CAZTSSe photovoltaic devices from 10.35% to 11.32%.