Efficient and Stable Planar n–i–p Sb₂Se₃ Solar Cells Enabled by Oriented 1D Trigonal Selenium Structures

Abstract

Abstract Environmentally benign and potentially cost‐effective Sb 2 Se 3 solar cells have drawn much attention by continuously achieving new efficiency records. This article reports a compatible strategy to enhance the efficiency of planar n–i–p Sb 2 Se 3 solar cells through Sb 2 Se 3 surface modification and an architecture with oriented 1D van der Waals material, trigonal selenium (t‐Se). A seed layer assisted successive close spaced sublimation (CSS) is developed to fabricate highly crystalline Sb 2 Se 3 absorbers. It is found that the Sb 2 Se 3 absorber exhibits a Se‐deficient surface and negative surface band bending. Reactive Se is innovatively introduced to compensate the surface Se deficiency and form an (101) oriented 1D t‐Se interlayer. The p‐type t‐Se layer promotes a favored band alignment and band bending at the Sb 2 Se 3 /t‐Se interface, and functionally works as a surface passivation and hole transport material, which significantly suppresses interface recombination and enhances carrier extraction efficiency. An efficiency of 7.45% is obtained in a planar Sb 2 Se 3 solar cell in superstrate n–i–p configuration, which is the highest efficiency for planar Sb 2 Se 3 solar cells prepared by CSS. The all‐inorganic Sb 2 Se 3 solar cell with t‐Se shows superb stability, retaining ≈98% of the initial efficiency after 40 days storage in open air without encapsulation.