Formation Mechanisms and Phase Stability of Solid-State Grown CsPbI3 Perovskites

Materials and interfaces properties optimization for high-efficient and more stable RbGeI3 perovskite solar cells: optoelectrical modelling

In this research work, we investigated the effects of a broad set of materials properties and external operating parameters on the opto-electrical output of a hybrid RbGeI3-based perovskite solar cell (PSC) as a means of enhancing its performance. We first performed a judicious numerical modelling of the reference cell with the following structure FTO/TiO2/RbGeI3/Spiro-OMeTAD/Ag, with data retrieved from the experiment. SCAPS program enables to model the device, considering charge carriers transport governing equations. Investigations are directed on addressing the current challenges that include thinner, less environmentally harmful, cost-effectiveness, and more stable solar devices over time. Analysis of the effects of different hole transport material (HTM) on current-voltage (J-V) and external quantum efficiency (QE) characteristics, helps to identify CuI as an ideal HTM. Optimal cell output were achieved by investigating the effects of metal contact work function, defect states, RbGeI3 thickness, light transmission/reflection at the front/back contact, as well as operating temperature. As a result, efficiency increased significantly from 10.11 to 18.10%, and fill factor that represents a stability indicator, increased from 63.68 to 76.95%. Moreover, an optimum open-circuit voltage Voc = 0.70 V and a high short-circuit current density of Jsc = 33.51 mA/cm2 were recorded. An additional study on the capture cross-section of charge carriers ([Formula: see text]) on PV characteristics, enabled to achieve a power conversion efficiency (PCE) of 29.71% and FF of 88% at a value of [Formula: see text] selected to be 10-22 cm2. This contribution aims at designing and producing thinner, more efficient, more stable and more environmentally clean and economically viable PSCs.

Phase Behavior and Role of Organic Additives for Self-Doped CsPbI3 Perovskite Semiconductor Thin Films

The phase change of all-inorganic cesium lead halide (CsPbI3) thin film from yellow δ-phase to black γ-/α-phase has been a topic of interest in the perovskite optoelectronics field. Here, the main focus is how to secure a black perovskite phase by avoiding a yellow one. In this work, we fabricated a self-doped CsPbI3 thin film by incorporating an excess cesium iodide (CsI) into the perovskite precursor solution. Then, we studied the effect of organic additive such as 1,8-diiodooctane (DIO), 1-chloronaphthalene (CN), and 1,8-octanedithiol (ODT) on the optical, structural, and morphological properties. Specifically, for elucidating the binary additive-solvent solution thermodynamics, we employed the Flory-Huggins theory based on the oligomer level of additives' molar mass. Resultantly, we found that the miscibility of additive-solvent displaying an upper critical solution temperature (UCST) behavior is in the sequence CN:DMF > ODT:DMF > DIO:DMF, the trends of which could be similarly applied to DMSO. Finally, the self-doping strategy with additive engineering should help fabricate a black γ-phase perovskite although the mixed phases of δ-CsPbI3, γ-CsPbI3, and Cs4PbI6 were observed under ambient conditions. However, the results may provide insight for the stability of metastable γ-phase CsPbI3 at room temperature.

Stable CsPbBr3 Nanocrystals—Decorated Nanoporous Gold for Optoelectronic Applications

Halide perovskite colloidal nanocrystals have recently gained much attention thanks to their superior stability compared with their bulk counterpart and to their unique optical properties. In this paper, two systems combining nanocrystals and nanoporous gold are studied to create an optimal metal semiconductor heterojunction that can be used in photocatalysis and photovoltaic devices. The perovskite degradation phenomenon is observed when the nanoporous gold powder is mixed into the hexane suspension of nanocrystals, while the charge separation efficiency is increased by synthesizing the nanocrystals directly onto the gold porous structure. The analysis of the structural and optical properties evidences an energy transfer efficiency of 47%, along with the high structural stability of the hybrid system.

Cryogenic Scintillation Performance of Cs4PbI6 Perovskite Single Crystals

All-inorganic Cs₄PbI₆ single crystals (SCs) is emerging scintillators for radiation detection. In this study, we report on the X-ray scintillation properties of Cs₄PbI₆ SCs at the temperature range of 50-290 K. The temperature-dependent radioluminescence (RL) spectrum and decay time were investigated. It was found that the RL spectra show very pronounced temperature-dependent changes in the overall shape. The RL intensity increases with a decrease in the temperature under X-ray excitation. The emission bands at 318, 360, and 554 nm are attributed to the near-band-edge emission in Cs₄PbI₆ SCs, the ³P₁ → ¹S₀ transition of the Pb²⁺ ion, and the emission of δ-CsPbI₃ aggregates dispersed in the Cs₄PbI₆ SC matrix, respectively. With decreasing temperature, the fast and slow decay times tend to slow down and are estimated to be 46.0 ns (33.22%) and 820 ns (66.78%) at 50 K, which are far superior to that of the common cryogenic scintillator. These cryogenic scintillation characteristics of Cs₄PbI₆ SCs demonstrate its potential for cryogenic detection.