Atomistic Description of the Impact of Spacer Selection on Two-Dimensional (2D) Perovskites: A Case Study of 2D Ruddlesden–Popper CsPbI3 Analogues

Abstract

Inorganic CsPbI3 perovskites have become desirable for use in photovoltaic devices due to their excellent optoelectronic properties and increased resilience to thermal degradation compared to organic-inorganic perovskites. An effective strategy for improving both the performance and the phase stability of CsPbI3-based perovskites is through introducing a diverse set of spacing cations separating inorganic layers in their two-dimensional (2D) analogues. In this work, CsPbI3-based 2D Ruddlesden-Popper perovskites were investigated using three aromatic spacers, 2-thiophenemethylamine (ThMA), 2-thiopheneformamidine (ThFA), and benzylammonium, fluorinated through para substitution (pFBA). Our findings highlight the importance of the local bonding environment between organic spacers and the PbI6 octahedra. Additionally, we demonstrated the importance of energetic alignment between electronic states on spacing cations and inorganic layers for optoelectronic applications. Furthermore, thermoelectric performance was investigated revealing a preference for p-type ThFA and n-type ThMA and pFBA configurations.