Optimization of Blade-Coated SnO₂ Electron Transport Layer via DOODA Modification for High-Performance Perovskite...

As a critical component of n-i-p perovskite solar cells (PSCs), the SnO₂ electron transport layer (ETL) faces challenges in colloidal stability and film uniformity when fabricated by blade-coating. Herein, 3, 6-Dioxaoctanedioic acid (DOODA) is introduced into SnO₂ colloidal ink to enhance dispersion stability for blade-coating, ensuring optimized coverage and morphology of the SnO₂ ETL. The results show that the carboxyl groups (-COOH) of DOODA coordinate with Sn⁴⁺ on the SnO₂ surface, anchoring the molecules onto the particle surface, while the ether segments (-O-) extend outward to create steric hindrance, improving the dispersion stability of SnO₂ colloids. Furthermore, the -OH groups form hydrogen bonds with SnO₂ surface oxygen, reducing oxygen vacancies and passivating surface defects. Meanwhile, -COOH passivates under-coordinated Pb²⁺ and I^- in the perovskite, reducing interfacial defects, promoting crystallization, and optimizing band alignment. The DOODA-modified device achieves a PCE of 24.64%, and large-area devices (0.99 cm²) reach 22.54%. Notably, the unencapsulated target device exhibits substantially enhanced stability, retaining 90.48% of its initial efficiency after 1944 h of aging in a nitrogen atmosphere, whereas the control device retains only 59.30%. This study provides a feasible strategy for the fabrication of high-quality ETLs using the blade-coating method.