Tin-based perovskite solar cells with a homogeneous buried interface

"Tin-based perovskite solar cells (TPSCs) have emerged as a promising non-toxic and environmentally friendly alternative to lead-based devices1-3, with certified power conversion efficiencies (PCEs) of inverted architectures now exceeding 16%4-8. Despite an ideal bandgap supporting a theoretical PCE over 33%, TPSCs still lag in performance and stability, partly due to suboptimal hole transport layers and poor buried interface that hinder hole extraction."

"Here, we report (E)-(2-(4',5'-bis(4-(bis(4-methoxyphenyl)amino)phenyl)-[2,2'-bithiophen]-5-yl)-1-cyanovinyl)phosphonic acid at the buried interface, using a molecular film to optimize hole transport layers in inverted TPSCs. This molecular film forms a homogeneous interfacial layer with well-matched energy level alignment, significantly enhancing hole extraction. Moreover, this approach creates a superwetting underlayer that guides the growth of uniform, high-quality Sn-based perovskite films with reduced defect density and minimized non-radiative recombination losses."

Tin-based perovskite solar cells (TPSCs) offer a non-toxic, environmentally friendly alternative with an ideal bandgap supporting theoretical PCEs over 33% but have been limited by performance and stability. A phosphonic-acid-terminated molecular film was applied at the buried interface to optimize hole transport layers in inverted TPSCs. The molecular film creates a homogeneous interfacial layer with well-matched energy level alignment, enhancing hole extraction. The film also forms a superwetting underlayer that guides growth of uniform, high-quality Sn-based perovskite films, reducing defect density and non-radiative recombination. Inverted small-area devices reached 17.89% PCE (certified 17.71% reverse scan), and encapsulated devices maintained over 95% of initial PCE after 1344.

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