Novel Lead-Free Material Cs₂PtI₆ with Narrow Bandgap and Ultra-Stability for Its Photovoltaic Application

Abstract

Lead halide perovskite has in recent years gained widespread interest due to its excellent physical and chemical properties, as well as superior optoelectronic performance. However, some restrictions still preclude full industrialization of the material, in particular toxicity issues and instability as a result to sensitivity to humidity. Lead-free all-inorganic double perovskite materials have thus recently become a focus of research. Herein, a new narrow bandgap lead-free double perovskite solar cell with a high-quality Cs 2 PtI 6 film is proposed. It exhibits an optical bandgap of 1.37 eV, absorption within a wide range of wavelengths, and a high absorption coefficient. Following optimization, the device displays a best power conversion efficiency of 0.72% with an opencircuit voltage of 0.73 V, a short-circuit current of 1.2 mA/cm 2 , and a fill factor of 0.82. Crucially, it also demonstrates excellent stability when exposed to extreme conditions such as high humidity, high temperature, and UV-light irradiation. Stability tests show that the PSCs can retain almost 80% of the original efficiency over 60 days stored in ambient temperature without any encapsulation, boosting prospects for applications of lead-free perovskite solar cells.

DFT study of X‐site ion substitution doping of Cs 2 PtX 6 on its structural and electronic properties

“…It can be seen from Table 2 that the hybrid functional bandgaps of the four perovskites are 3.31, 2.33, 1.39 and 2.07 eV, respectively. As for Cs 2 PtI 6 , the calculated HSE bandgap is 1.39 eV, which is roughly consistent with the experimental value of 1.37 eV, proving the reliability of the calculation results 10 . According to the trend in the bandgaps calculated by the PBE method, we can predict that other unscanned HSE bandgaps of the compounds will change in a small range.…”

“…As for Cs 2 PtI 6 , the calculated HSE bandgap is 1.39 eV, which is roughly consistent with the experimental value of 1.37 eV, proving the reliability of the calculation results. 10 According to the trend in the bandgaps calculated by the PBE method, we can predict that other unscanned HSE bandgaps of the compounds will change in a small range. The bandgap of Cs 2 PtI y Cl 6Ày is between 1.39 and 3.31 eV, while that of Cs 2 PtI y Br 6Ày and Cs 2 PtBr y Cl 6Ày are from 1.39 to 2.33 eV and 2.33 to 3.31 eV, respectively.…”

“…Our group 10 has synthesized large‐size Cs 2 PtI 6 single crystal and high‐quality Cs 2 PtI 6 thin film by a simple method and studied its photovoltaic properties. In the same year, Hamdan et al 32 and Sajjad et al 33 explored the extraordinary stability of Cs 2 PtI 6 in various environments by means of experiment and first‐principle calculation.…”

“…8,9 Although superior photovoltaic properties have been realized, some challenges still exist with the HPSCs, that is, the toxicity of lead (Pb) and the perovskites that suffer from poor chemical stability in air. 10,11 Replacing organic components in the perovskite materials with inorganic components may be an ultimate solution to the problem of thermal instability. [12][13][14] Therefore, many researchers have developed a new type of all-inorganic Cs-based halogenated perovskite CsBX 3 by oxygen evolution in water.…”

Large-Gap Quantum Anomalous Hall Effect in Monolayer Halide Perovskite

“…Similar structure can be found in (111) bilayer transition metal oxides perovskite [27]. The alkali metal and halogen atoms at the outermost layers form a shield to protect the inner buckled honeycomb lattice composed of transition metal atoms from degradation of environment in monolayer A 3 B 2 C 9 , leading to high stability of the structures as experimentally synthesized halide perovskites Cs 3 In 2 Cl 9 and Cs 2 PtI 6 [30,43]. The structural stability of monolayer A 3 B 2 C 9 is also confirmed by phonon spectrum calculations [see Fig.…”