Researchers from China's Beihua University have developed a heterovalent doping approach to achieve controllable p-type behavior in lead halide perovskites, offering a promising route toward more efficient perovskite-based solar cells. Their work focuses on the systematic substitution of group-IB metal ions - gold (Au⁺), silver (Ag⁺), and copper (Cu⁺) - into the B-site of the all-inorganic perovskite CsPbBr₃ lattice.
The motivation behind the study lies in a well-known hurdle for perovskite optoelectronics: while intrinsic CsPbBr₃ exhibits excellent light absorption and stability, it lacks effective p-type conductivity control, which is essential for forming high-performance p–n junctions in solar devices. To overcome this, the Beihua team applied first-principles density functional theory (DFT) to model how different dopant ions and concentrations influence the material’s structure, electronic configuration, and optical response.
Computational results show that when Pb²⁺ is partially replaced by group-IB cations, the resulting CsMₓPb₁₋ₓBr₃ (M = Au, Ag, Cu) compounds remain thermodynamically stable, suggesting that they can be synthesized experimentally. The introduction of heterovalent dopants raises the valence band energy, causing it to intersect the Fermi level — a clear indicator of p-type semiconducting behavior. Moreover, the choice and proportion of dopant enable fine-tuning of the bandgap between 1.10 eV and 2.51 eV, broadening light absorption from the visible to near-infrared range.
From a performance standpoint, the doped compounds exhibit a higher spectral-limited maximum efficiency than pristine CsPbBr₃, highlighting their strong photovoltaic potential. The improved efficiency stems from enhanced charge carrier concentration and optimized energy band alignment, both of which facilitate more effective charge separation and transport.
This study provides a theoretical foundation for p-type engineering in inorganic perovskites and points toward practical pathways to design balanced, stable p–n junction devices. If realized experimentally, such doped perovskites could help bridge the gap toward scalable, high-efficiency all-inorganic perovskite solar cells suitable for commercial application.
