Chlorine Incorporation in the CH₃NH₃PbI₃ Perovskite: Small Concentration, Big Effect

Abstract

The role of chlorine doping in CHNHPbI represents an important open issue in the use of hybrid perovskites for photovoltaic applications. In particular, even if a positive role of chlorine doping on perovskite film formation and on material morphology has been demonstrated, an inherent positive effect on the electronic and photovoltaic properties cannot be excluded. Here we carried out periodic density functional theory and Car-Parrinello molecular dynamics simulations, going down to ∼1% doping, to investigate the effect of chlorine on CHNHPbI. We found that such a small doping has important effects on the dynamics of the crystalline structure, both with respect to the inorganic framework and with respect to the cation libration motion. Together, we observe a dynamic spatial localization of the valence and conduction states in separated spatial material regions, which takes place in the 10 ps time scale and which could be the key to ease of exciton dissociation and, likely, to small charge recombination in hybrid perovskites. Moreover, such localization is enhanced by chlorine doping, demonstrating an inherent positive role of chlorine doping on the electronic properties of this class of materials.

The Role of Chloride Incorporation in Lead‐Free 2D Perovskite (BA)2SnI4: Morphology, Photoluminescence, Phase Transition, and Charge Transport

“…Figure b displays the XPS spectrum for the (BA) 2 SnI 4− x Cl x crystals with the I:Cl ratio of 1:3 in the precursor solution, which clearly shows that the Cl 2p electrons are present. Close inspection of Cl (2p) peak indicates that two peaks are present with the binding energies of 197.7 and 199.4 eV (Figure c), corresponding to the energy of ClSn bonds, which is another strong evidence that Cl element has been incorporated into the crystal lattice of (BA) 2 SnI 4 . The presence of Cl element in the resultant (BA) 2 SnI 4− x Cl x has been further verified by EDS studies, which reveals that the Cl element gradually increases as the ratio of I to Cl in precursor solution increases (Figure S2, Supporting Information).…”

Efficient Red Perovskite Light‐Emitting Diodes Based on Solution‐Processed Multiple Quantum Wells

“…This results in a higher content of chlorine residue in the MQW film. It is also worth mentioning that it has been theoretically and experimentally validated that chlorine residue can positively impact the electronic properties of perovskite films by passivating the defects and reduce charge recombination . Transient PL measurement shows that the carrier lifetime is increased in NCPI 6 Cl (Figure ; Figure S5, Supporting Information), indicating Cl helps to reduce the defects in the MQW structures .…”

Design of cyclopentadithiophene-based small organic molecules as hole selective layers for perovskite solar cells

“…This research line was upraised from the report by Miyasaka et al 1 in 2009 using methyl ammonium lead iodide (CH3NH3PbI3) perovskite as a light harvesting material in dye sensitized-solar cells. The intriguing properties of perovskites solar cells (PSCs) 2 , such as simple and customizable devices architecture, versatility in deposition process 3 , tuneable optical absorption by anion or cation substitution 4,5 in perovskite structure, designing of the new charge selective contacts 6 , have attracted chemist, physicist, engineers to make substantial progress in this new field 7,8 . Organic-inorganic hybrid perovskites show excellent opto-electrical properties such as high absorption coefficient, long electron and hole diffusion lengths, and high charge-carrier mobilities 9 .…”