Bidirectional Chemo-Mechanical Interface Stabilization in Perovskite Solar Cells

The interface structures between dissimilar layers in perovskite solar cells (PSCs) are prone to the concurrent occurrence of lateral (in-plane) chemical aggregation and vertical (out-of-plane) mechanical delamination. This issue severely affects long-term optoelectronic processes in PSCs, and it has not been addressed holistically. Herein, we introduce an ultrathin interfacial layer of 1,3,6,8-pyrenetetrasulfonic tetrasodium salt (PTS) to stabilize the perovskite/C60 interface at the molecular level. The sulfonate groups in PTS molecules anchor to the perovskite interface, while the parallelly aligned pyrene cores establish robust π-π interactions with C60 molecules. The reconstructed interface enhances the interfacial adhesion and restricts the mobility of C60 molecules, enabling a bidirectional chemo-mechanical interface stabilization (BCIS) mechanism at the perovskite/C60 interface. The resultant PSCs deliver power conversion efficiencies (PCEs) of up to 26.53%, showing 96% PCE retention after 1,000 h maximum-power-point tracking (ISOS-L-1l), and 91% PCE retention after 300 thermal cycles (-40 to 85 °C, IEC61215 MQT11). The scalability of PTS treatment is demonstrated by the 818 cm2 (aperture area) perovskite solar modules (PSMs) with PCEs over 20% using industrial-compatible manufacturing processes under 55% relative humidity (RH). This work underscores bidirectional interface engineering as a critical strategy for advancing commercially viable perovskite photovoltaics.