Affiliation:
1. School of Photovoltaic and Renewable Energy Engineering University of New South Wales Sydney New South Wales Australia
2. Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang Liaoning China
3. School of Chemical Engineering University of New South Wales Sydney New South Wales Australia
Abstract
AbstractThe liquid‐phase‐assisted grain growth (LGG) process is a promising strategy to fabricate large‐grain pure sulfide Cu2ZnSnS4 (CZTS) layers that span the absorber thickness and improve the carrier collection efficiency in photovoltaic devices. Li doping is an effective route to promote such LGG process of Cu2ZnSn(S,Se)4 (CZTSSe) as it can provide liquid Li‐Se phase facilitating the growth of large‐grain CZTSSe. However, the detailed function of the added Li in grain growth has rarely been investigated in both CZTS and CZTSSe, as the reported in situ, and pre‐deposition doping strategies usually suffer from substantial Li losses during the spin‐coating process and/or the high‐temperature sulfurization process. Herein, by monitoring the temperature‐dependent Li loss during the sulfurization process, we demonstrate that a small proportion of the added Li can remain at the CZTS film from the early sulfurization stage and provide Li‐S flux to promote the LGG process. An encouraging efficiency of 10.53%, with a remarkably high short‐circuit current density of 22.6 mA/cm2 and open‐circuit voltage of 0.744 V, is achieved by a significantly enlarged grain size of 3 μm with Li addition. This work could enhance the knowledge of employing Li‐S as flux for growing large‐grain chalcogenide absorbers for high performance devices with better carrier transport.
Funder
Australian Centre for Advanced Photovoltaics
Australian Renewable Energy Agency