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.

Charge Carrier Dynamics at the Interface of 2D Metal–Organic Frameworks and Hybrid Perovskites for Solar Energy Harvesting

“…The resulting structures had an average Pb–I bond distance of 3.23 and 3.24 Å for the UMCM-309a and ZrL3 interfaced MAPbI 3 systems, respectively. Additionally, for both systems, cis and trans Pb–I–Pb bond angles center around 90° and 175°, respectively (Figure S1), which are in line with previous investigations of MAPbI 3 and its 2D analogues. − The density of states (DOS) of UMCM-309a@MAPbI 3 and its thiol-functionalized analogue ZrL3@MAPbI 3 are pictured in Figures a and d, respectively. Contributions from the perovskite subsystem remained consistent for both structures with a gap between frontier perovskite-localized eigenstates of approximately 2.2 eV, marking the transition between occupied states with I­(p) and Pb(s) character and unoccupied states with Pb­(p) character.…”

Two-Dimensional Double Perovskites in the Dion–Jacobson Phase Alleviate Parity Forbidden Transitions for Photovoltaic Applications

“…All BTE calculations are carried out in the relaxation time approximation as implemented in BoltzTraP2 . Deformation potential theory was used to obtain approximate relaxation times for the 18 perovskite systems of interest as detailed in eqs and , carried out in an identical manner to our previous work. , Here the index i corresponds to the charge carrier type and e and h to electrons and holes, respectively. C 2D represents the in-plane stiffness constant, and E VBM , E CBM are deformation potentials at the valence and conduction band edge, respectively, for which more information regarding the computational details can be found in the Computational Methods.…”

Nucleation and Crystallization in 2D Ruddlesden‐Popper Perovskites using Formamidinium‐based Organic Semiconductor Spacers for Efficient Solar Cells

“…[15][16][17][18][19][20][21][22] Trivedi et al have proposed that employing an FA-based spacer, as opposed to an MA-based spacer, could lead to the reduction in the band gap of 2D perovskites. [23] This reduction is attributed to the strong localization of electronic states to the FA-based spacer, specifically at the conduction band edge. Moreover, the aromatic spacers with the delocalized π-electrons exhibit a large dielectric constant, reducing the dielectric mismatch between organic spacers and the adjacent inorganic octahedral layers.…”

“…Trivedi et al. have proposed that employing an FA‐based spacer, as opposed to an MA‐based spacer, could lead to the reduction in the band gap of 2D perovskites [23] . This reduction is attributed to the strong localization of electronic states to the FA‐based spacer, specifically at the conduction band edge.…”