High Performance Inverted RbCsFAPbI₃ Perovskite Solar Cells Based on Interface Engineering and Defects Passivation

Abstract

PSCs have sparked widespread concern with their quick advancement in photovoltaic performance. Their PCEs have advanced from 3.8% to 25.7% in recent years. [1,2] In modern PSCs, methylammonium (MA) and formamidinium (FA) are two prevalent organic cations. [3][4][5][6] Recently lead and lead/tin mixed perovskite solar cells are attaining immense attraction due to their excellent band tunability. [7] Although FAPbI 3 's optical bandgap (1.45-1.48 eV) [8,9] is closer to the predicted bandgap (1.34 eV) than MAP-bI 3 's (1.58 eV). [10] There is a complication with using FAPbI 3 directly in PSCs since it converts to a photo inactive (δ-FAPbI 3 ) phase at ambient temperature. [11,12] In a thorough study, the α-to-δ phase transition was effectively inhibited by Rb + , [13,14] Cs + , [11,15] MA + , [5,16] and Br − incorporation [15,16] into the FAPbI 3 crystal lattice to form a more stale cubic perovskite structure. To prevent δ-FAPbI 3 formation, MA cations are detrimental to the device's thermal stability, [13] while adding Br − will cause a blue shift in the bandgap. [10] As a result, the favored cations are the thermally stable Cs + , Rb + , FA + , and I − as the chosen halide anion.Rubidium (Rb) is a member of the alkali metal family with a smaller ionic radius (1.52 Å) and is located above cesium in the alkali group. However, the side phase, that is, RbPbI 3 melted and disintegrated at 714 K without going through a phase shift to black perovskite when heated ≈298 and 634 K. It preserved yellow-δ-phase orthorhombic structure at such conditions. [17] To determine how the gradual replacement of Rb for Cs impacts the structure, thermodynamics, and electrical characteristics, Jung et al. used calculations based on a density-functional theory of the first principle. [18] Rubidium and guanidinium (GA) as A-site cations were used by Prochowicz et al. to study the effect of open-circuit voltage (V OC ) in PSCs, [19] determining that the type of the A-site cation controls the V OC of PSCs. By constructing a 2D Ruddlesden-Popper layer on top of a 3D Rb + doped triple cation perovskite, researchers have created a novel 3D/2D planar bi-layer perovskite. [20] The inclusion of Rb + cation lowers the work function, resulting in slightly higher PCE (>20%) than its 3D equivalents (19.5%). As a result of their Lead halide-based perovskites solar cells (PSCs) are intriguing candidates for photovoltaic technology due to their high efficiency, low cost, and simple fabrication processes. Currently, PSCs with efficiencies of >25% are mainly based on methylammonium (MA)-free and bromide (Br) free, formamide lead iodide (FAPbI 3 )-based perovskites, because MA is thermally unstable due to its volatile nature and Br incorporation will induce blue shift in the absorption spectrum. Therefore, MA-free, Br-free formamidine-based perovskites are drawing huge research attention in recent years. The hole transporting layer (HTL) is crucial in fabricating highly efficient and stable inverted p-i-n structured PSCs by enhancing charge extraction, lower...

Surface pre-sacrifice behavior of thiourea-based 2D perovskites for high-performance perovskite solar cells

“…However, due to the singularity of organic passivation molecules, improvements in both efficiency and stability remain limited. 22,23 In recent years, using organic ammonium salt cations as passivators to grow 2D perovskites in situ and construct 2D/3D perovskite structures has proven to be a viable strategy which can balance the advantages of both organic cation passivators and 2D perovskites. 24–27 Through healing defects and enhancing charge-carrier extraction, Nazeeruddin et al have prepared efficient n -butylammonium iodide (BAI)-based 2D/3D heterojunction PSCs with a certified PCE of 25.04% and prominent operational stability under continuous light illumination.…”