Efficient Double Buffer Layer Sb₂ (Se_xS_1–x)₃ Thin Film Solar Cell Via Single Source Evaporation

Abstract

Sb 2 (Se x S 1–x ) 3 has been proven a very promising light absorbing material for photovoltaic applications due to its high stability, tunable band gap, non‐toxic element, and high extinction coefficient. For Sb 2 (Se x S 1–x ) 3 alloy film deposition, the authors develop a single source based rapid‐thermal‐evaporation (RTE) method instead of the traditional in‐situ sulfurization or double source co‐evaporation based RTE method. The absorber band gap can be precisely tuned from 1.1 to 1.7 eV by simply varying the molar ratio of Sb 2 Se 3 and Sb 2 S 3 source powder. From the systematical composition screening, FTO/CdS/Sb 2 (Se 0.68 S 0.32 ) 3 /Au devices show higher power conversion efficiency (PCE ∼ 4.17%) when compared with other absorber compositions based devices. In order to achieve thinner ETL layers and simultaneously avoid pinholes led by rough FTO surface, we introduce for the first time double buffer layer in the Sb 2 (Se 0.68 S 0.32 ) 3 device system which could further improve the device efficiency from 4.17% to 5.73%. The double buffer layer ZnO/CdS helped to form graded energy band alignment, suppress charge recombination and efficiently extract electrons. The devices obtained higher J sc and V oc supported by various physical characterization analyses. The facile single source deposition method, efficient double buffer layer device structure and notable PCE are expected to pronouncedly promote antimony chalcogenide device development.