image: 3-cyanopropyltrimethoxysilane (CN-TMOS) molecules anchoring at the buried interface between the perovskite layer and the hole transport layer. The CN-TMOS strengthens interfacial adhesion, reduces defects, and improves charge extraction, leading to higher efficiency and stability.
Credit: ©Science China Press
Perovskite tandem solar cells (TSCs) promise to surpass the efficiency limits of traditional silicon photovoltaics, but wide-bandgap (WBG) perovskite subcells often suffer from high open-circuit voltage (VOC) losses due to interfacial defects and non-radiative recombination. A team led by researchers from Zhengzhou University and the Chinese Academy of Sciences has now developed a solution: a silane coupling agent strategy that dramatically improves interfacial adhesion and charge extraction in WBG-PSCs.
The study, published in Science Bulletin, demonstrates how trimethoxysilane (TMOS) molecules, specifically 3-cyanopropyltrimethoxysilane (CN-TMOS), strengthen the buried interface between the perovskite and hole transport layer (HTL). CN-TMOS not only enhances chemical bonding but also regulates perovskite crystallization, reducing defects and non-radiative recombination.
Key achievements include:
High VOC: 1.345 V (bandgap: 1.77 eV), with VOC loss reduced to 0.425 V.
High efficiency: 19.69% PCE in single-junction WBG-PSCs and 28.45% in all-perovskite TSCs.
Excellent stability: TSCs retained 90% PCE after 500 hours under continuous illumination.
Experimental and theoretical analyses revealed that CN-TMOS’s electron-withdrawing cyanide group (-CN) passivates interfacial defects and optimizes energy level alignment, enabling efficient hole extraction. The team further validated the universality of this approach by integrating the optimized WBG-PSCs into monolithic tandem devices, achieving current matching and minimal VOC-loss.