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

Abstract

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.

9.6%-Efficient all-inorganic Sb2(S,Se)3 solar cells with a MnS hole-transporting layer

“…The effective carrier mobility in our Sb 2 (S,Se) 3 absorber may be even lower than the value reported in ref. 8. Therefore, a high-quality HTL is essential for efficient carrier collection of high-efficiency devices.…”

“…6,7 Due to the highly anisotropic quasi 1D structure and the associated low effective carrier mobility of Sb 2 (S,Se) 3 , an n-i-p device structure with a fully depleted absorber and enhanced carrier collection via an extended built-in electric eld is essential for achieving high efficiencies. 8 The p-type holetransporting layer (HTL) plays a key role in determining device performance by generating a built-in electric eld at the rear interface and extracting photogenerated holes from the Sb 2 (S,Se) 3 absorber to the counter electrode. Spiro-OMeTAD is the most widely used hole-transporting material (HTM) to date, inheriting from perovskite and dye-sensitized solar cells.…”

“…The highly anisotropic carrier transport in Sb 2 (S,Se) 3 and extremely low effective carrier mobility determine that this material requires a strong built-in electric eld to facilitate carrier extraction. 8,19 Therefore, in our communication, a MnS HTL was deposited using up-scalable thermal evaporation followed by post-annealing treatment to specially meet these requirements. This all-inorganic Sb 2 (S,Se) 3 solar cell shows superior stability and comparable efficiency compared to the Sb 2 (S,Se) 3 solar cell employing a Spiro-OMeTAD HTL, highlighting the great potential of MnS as a non-toxic, low cost ($$4/g) and stable HTL for efficient Sb 2 (S,Se) 3 and other n-i-p or p-i-n architecture solar cells.…”

Boosting VOC of antimony chalcogenide solar cells: A review on interfaces and defects

“…Recently, several groups suggested that an n-i-p device architecture is likely a promising option for Sb 2 X 3 solar cells. [26][27][28][29] Although a lot of works on the fabrication of Sb 2 X 3 absorber with different structures have been done, there is still no consensus on the optimal configuration.…”

“…Therefore, efforts should be made on fabricating highly crystalline antimony chalcogenide absorber films with [hk1] preferred orientation, and less dislocations, which is beneficial to maximize carrier mobility. [ 26 ]…”