Efficient All‐Inorganic Sb2S3 Solar Cells with Matched Energy Levels Using Sb2Se3 as Hole Transport Layers

Sb 2 S 3 has emerged as a promising light‐absorbing material due to its nontoxicity, low cost, high stability, and absorption coefficient. However, the absorption spectrum ranges and back‐contact barrier between Sb 2 S 3 and Au strongly limit the device performance. p‐type Sb 2 Se 3 has a similar lattice structure and properties as Sb 2 S 3 , obtaining absorption expansion and ohmic back contact. Herein, efficient all‐inorganic planar Sb 2 S 3 solar cells with the addition of Sb 2 Se 3 layers are fabricated. The functions of Sb 2 Se 3 as cooperative absorber (400 nm) and hole transport layers (HTL, 80 nm) are further explored. Systematic characterizations indicate that the junction quality and depletion widths of the device with the addition of Sb 2 Se 3 are improved by forming a p–i–n structure. As a result, the all‐inorganic Sb 2 S 3 solar cell with a Sb 2 Se 3 HTL greatly increases the power conversion efficiency from 2.7% to 5.8% and the fill factor from 40% to 55.4%. The additional Sb 2 Se 3 /Au interface with matched energy‐level alignments reduces the back‐contact barrier and facilitates hole transport and collection. The present design and methods promote the development of Sb 2 S 3 solar cells.