Investigation of Opto-Electronic Properties and Stability of Mixed-Cation Mixed-Halide Perovskite Materials with Machine-Learning Implementation

Abstract

The feasibility of mixed-cation mixed-halogen perovskites of formula AxA’1−xPbXyX’zX”3−y−z is analyzed from the perspective of structural stability, opto-electronic properties and possible degradation mechanisms. Using density functional theory (DFT) calculations aided by machine-learning (ML) methods, the structurally stable compositions are further evaluated for the highest absorption and optimal stability. Here, the role of the halogen mixtures is demonstrated in tuning the contrasting trends of optical absorption and stability. Similarly, binary organic cation mixtures are found to significantly influence the degradation, while they have a lesser, but still visible effect on the opto-electronic properties. The combined framework of high-throughput calculations and ML techniques such as the linear regression methods, random forests and artificial neural networks offers the necessary grounds for an efficient exploration of multi-dimensional compositional spaces.

Optoelectronic and stability properties of quasi-2D alkylammonium based perovskites

“…A number of theoretical and experimental investigations described in ref. 4 confirm the overall picture of an enhanced stability for Br-based perovskites compared to I-based ones, which is similar for both 3D and 2D perovskites, e.g. by Pistor et al , 33 Brunetti et al , 34 Ciccioli et al 35 and McGovern et al 36 Some 3D compounds were shown to be less stable ( e.g.…”

“…This is in contrast with the extrinsic degradation, where the use of chlorine is beneficial, the improvement with respect to iodine based systems being similar to the one of bromine based compounds (5–6%). The overall behavior of the stability with respect to the halogen type is, to some degree, similar to one corresponding to 3D perovskites: 4 for the intrinsic mechanism, the stability increases in the sequence I ↗ Cl ↗ Br [(PA) 2 PbX 4 ] and Cl ↗ I ↗ Br [(A) 2 (MA)Pb 2 X 7 ], while for the extrinsic mechanism we have I ↗ Cl ≈ Br. A number of theoretical and experimental investigations described in ref.…”

“…based on hydroxylammonium and hydrazinium), which was also experimentally confirmed. Recently, the MA 1− x EA x PbI 3 mixed perovskite system, identified in our previous study 4 as one strong candidate for improved stability and photovoltaic performance, was theoretically and experimentally confirmed. 37…”

Mixology of MA1–xEAxPbI3 Hybrid Perovskites: Phase Transitions, Cation Dynamics, and Photoluminescence

“…In this work, we use a suite of experimental and theoretical techniques to study a promising novel mixed-cation MA 1– x EA x PbI 3 perovskite system. The hybrid compounds containing EA cations are gaining significant attention for their improved stability and photovoltaic performance. − ,− Pure EAPbI 3 crystallizes into the orthorhombic ( Pnma ) symmetry − with the anionic component having a 1D architecture composed of false[ normalP normalb normalI 3 false] n − columns which are built of face-sharing octahedra; however, no information is available on the structural phase transitions of this compound. The band gap of this compound is 2.2 eV, making it suitable for photovoltaic applications .…”

Mixology of MA1-xEAxPbI3 Hybrid Perovskites: Phase Transitions, Cation Dynamics and Photoluminescence

“…The hybrid compounds containing EA cations are gaining significant attention for their improved stability and photovoltaic performance. [24][25][26][27][28][29][42][43][44] Pure EAPbI 3 crystallizes into the orthorhombic (P nma) symmetry [45][46][47] with the anionic component having a 1D architecture composed of [PbI 3 ]n columns which are built of face-sharing octahedra, however no information is available on the structural phase transitions of this compound. The band gap of this compound is 2.2 eV making it suitable for photovoltaic applications.…”