Operational stability remains a critical challenge for organic-inorganic hybrid perovskite solar cells (PSCs). Recently, the use of low-dimensional perovskite has emerged as a promising route to enhance the device robustness. It is found that the 1D/3D heterojunction has a significant impact on the stability, while the role of spacer cations in the 1D/3D heterojunction regulation is poorly understood. Here, we report the synthesis of two new types of 1D perovskite single crystals, (BZ)2Pb1.5I4, (TFBZ)PbI3, using benzamidinium (BZ) and (trifluoromethyl) benzamidinium (TFBZ) as spacer cations. Our analysis reveals that the trifluoromethyl groups in TFBZ contribute to extensive hydrogen-bond networks and confer a high dipole moment. These features strengthen the interaction between TFBZ and inorganic PbI64- skeleton, resulting in high structure stability and orientationally crystallized 1D perovskites. Furthermore, the incorporation of 1D (TFBZ)PbI3 forms a robust and high-quality 1D/3D heterojunction interface, facilitated by stable 1D phase, favorable lattice matching, strong interface binding, and effective defect passivation. Accordingly, the resulting TFBZ-based 1D/3D hybrid PSCs achieve a power conversion efficiency of 25.54%, while maintaining expectational operational and thermal stability. This work provides a design strategy to control the microstructure of a 1D/3D heterojunction, enabling highly efficient and stable perovskite photovoltaics.
Hao et al. (Tue,) studied this question.