Inorganic A‑site cations improve the performance of band‑edge carriers in lead halide perovskites

In lead halide perovskites,organic A-site cations are generally introduced to fne-tune the properties.One of the questions under debate is whether organic A-site cations are essential for high-performance solar cells.In this study,we compare the band edge carrier dynamics and difusion process in MAPbBr_(3)and CsPbBr_(3)single-crystal microplates.By transient absorption microscopy,the band-edge carrier difusion constants are unraveled.With the replacement of inorganic A-site cations,the difusion constant in CsPbBr_(3)increases almost 8 times compared to that in MAPbBr_(3).This work reveals that introducing inorganic A-site cations can lead to a much larger difusion length and improve the performance of band-edge carriers.

Fabrication of mixed perovskite organic cation thin films via controllable cation exchange

Here in this paper, we demonstrate a facile technique for creating the mixed formamidinium（HN = CHNH_3~＋, FA~＋）and methylammonium（CH_3NH_3~＋, MA~＋） cations in the lead iodide perovskite. This technique entails a facile drop-casting of formamidinium iodide（FAI） solutions on as-prepared MAPbI_3 perovskite thin films under the controlled conditions,which leads to controllable displacement of the MA~＋ cations by FA~＋ cations in the perovskite structure at room temperature. Uniform and controllable mixed organic cation perovskite thin films without a ＂bi-layered＂ or graded structure are achieved. By applying this approach to photovoltaic devices, we are able to improve the performances of devices through extending their optical-absorption onset further into the infrared region to enhance solar-light harvesting. Additionally,this work provides a simple and efficient technique to tune the structural, electrical, and optoelectronic properties of the light-harvesting materials for high-performance perovskite solar cells.

Preparation of High-capacity, Monodisperse Polymeric Weak Cation Exchange Packings Using Surface-initiated Atom Transfer Radical Polymerization and Its Chromatographic Properties

A novel stationary phase for weak cation exchange （WCX） chromatography was prepared by ＂grafting from＂ strategy. Surface initiated atom transfer radical polymerization （ATRP） of acrylic acid （AA） was conducted in toluene medium, starting from the macromolecule initiators of poly（4-vinylbenzyl chloride-co-divinylbenzene） （PcMs/DvB） beads, The amounts of poly（acrylic acid） grafted chains with different ATRP formulations were calculated based on the elemental analyses. The poly（acrylic acid） grafted beads obtained with different ATRP formula- tions were tried as chromatographic packings in the separation of proteins by ion-exchange chromatography. The effect of the poly（acrylic acid） grafted chain lengths on PCMS/DVB beads for the separation of proteins was investigated in details. Simultaneously, characterization of the column was investigated as ion chromatographic stationary phase for the separation of inorganic cations. The results show that poly（acrylic acid） grafted columns had excellent performance for separation of proteins and inorganic cations. The highest of the dynamic capacity of the column was 35.55 mg/mL. The columns were provided with high column efficiency.