Engineering Chalcogenide-Containing Spacers: Modulating Internal Interactions for Enhanced Performance and Stability in Ruddlesden–Popper Perovskite Devices

Two-dimensional
(2D) Ruddlesden–Popper (RP) halide
perovskites
are promising for optoelectronic applications due to their enhanced
stability compared to 3D versions. However, their practical application
is still hindered by the inherent instability arising from weak interactions
between adjacent organic layers. To address this challenge, we engineered
2D RP perovskites using four organic spacers: 3-thiophene-methylammonium
(3-TMA) and 3-furan-methylammonium (3-FMA), with 2-thiophene-methylammonium
(2-TMA) and 2-furan-methylammonium (2-FMA) as controls. Our findings
highlight that the heteroatom type (S vs O) and spacer regiochemistry
significantly influence interaction strength. Thiophene-based spacers
bond more robustly to inorganic layers than furan-based ones. Notably,
shifting the thiophene spacer configuration from 2-TMA to 3-TMA markedly
strengthens interactions between organic layers, improving RP perovskite
stability under ambient and thermal conditions. Utilizing the substantial
dipole moment of the optimized 3-TMA spacer, we developed an enhanced
performance perovskite photodetector with a responsivity of 153 mA/W
and detectivity of 1.7 × 1010 Jones. This study offers
insights into RP perovskite stability and guides the design of durable
perovskite devices through strategic spacer engineering.