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초록

Being placed near the perovskite grain boundaries, pyrene molecules reduce PbI6 octahedral tilting by controlling the orientations of the formamidinium (FA) cations within the lattice. Pyrene treatment immobilizes FA cations, reduces octahedral tilting, prevents their uncontrolled loss during film formation, and promotes the formation of pure α-formamidinium lead triiodide (FAPbI3). Using confocal fluorescence lifetime imaging microscopy (FLIM), we observed reduced electron-phonon coupling and a uniform spatioenergetic landscape, indicating enhanced structural rigidity of FAPbI3. Additionally, direct visualization of the exciton transport process revealed the significance of the stabilized octahedral cage for the carrier transport process. Consequently, we achieved a remarkable power conversion efficiency of 25.7% (certified 25.64%). The devices exhibited outstanding intrinsic stability, retaining over 94% of their initial current with encapsulation for over 3,400 h, while the unencapsulated devices also maintained over 90% for 2,000 h.

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