Defect-Resolved Effective Majority Carrier Mobility in Highly Anisotropic Antimony Chalcogenide Thin-Film Solar Cells

Majority carrier mobility is one of the most fundamental and yet important carrier transport parameters determining the optimal device architecture and performance of the emerging antimony chalcogenide solar cells. However, carrier mobility measurements based on the Hall effect have limitations for these highly anisotropy materials due to the discrepancy of transport directions under Hall measurement and device operation. Herein, a defect-resolved mobility measurement (DRMM) method enabling the evaluation of effective majority carrier mobility from a working device without such limitations is presented. Using this method, comprehensive information about the carrier transport in representative Sb2S3 and Sb2Se3 solar cells is extracted. Though with preferred [hk1]-crystalline orientation, Sb2S3 and Sb2Se3 still suffer from extremely low carrier mobility and low carrier density, respectively, resulting in large bulk resistance and poor carrier collection efficiency. Further crystalline structure analysis discloses that crystalline defects such as dislocations may significantly constrain carrier transport in these low-dimensional materials. These results suggest that a p-i-n device architecture with fully depleted absorber is a promising optimization approach for further efficiency advances of antimony chalcogenide solar cells.

Automated summary

This study introduces a defect-resolved mobility measurement method to evaluate the effective majority carrier mobility in antimony chalcogenide solar cells. It was found that despite the preferred crystal orientation, Sb2S3 and Sb2Se3 have extremely low carrier mobility and density, resulting in high bulk resistance and poor carrier collection efficiency. Further analysis reveals that crystalline defects like dislocations may significantly restrict carrier transport in these low-dimensional materials.