Electrical engineering

Nanotechnology

Organic chemistry

Energy conversion efficiency

Thermal stability

Engineering

Perovskite (structure)

Catalysis

Lewis acids and bases

Composite material

Chemistry

Materials science

Siloxane

Layer (electronics)

Photovoltaic system

Grain boundary

Passivation

Chemical engineering

Optoelectronics

Polymer

Microstructure

ACS Energy Letters

Here we report an efficient and reproducible multifunctional additive engineering strategy via methoxysilane cross-linking agents functionalized by the different terminal group, moderate electron-donating −SH, weak electron-donating −CH3, or strong electron-withdrawing −CN, into a PbI2 precursor solution. The power conversion efficiency (PCE) is increased from 18.4 to 20.8% after introduction of (3-mercaptopropyl)trimethoxysilane (MPTS) containing a −SH group as a consequence of improved voltage and current density, while 3-cyanopropyltriethoxysilane (CPTS) containing a −CN group deteriorates the overall photovoltaic performance. Moreover, −SH in MPTS is found to passivate defects effectively through a Lewis acid–base interaction with PbI2, resulting in a larger grain size and a longer carrier lifetime. Owing to the formation of a cross-linking siloxane network as a protective layer on the grain boundary, the thermal and moisture stability of the device are improved remarkably. The present work provides a guideline for multifunctional additive engineering for the purpose of simultaneous achievement of a high PCE and long-term stability.

Importance of Functional Groups in Cross-Linking Methoxysilane Additives for High-Efficiency and Stable Perovskite Solar Cells