Dual Passivation of CsPbI3 Perovskite Nanocrystals with Amino Acid Ligands for Efficient Quantum Dot Solar Cells

Aromatic amine-assisted pseudo-solution-phase ligand exchange in CsPbI3 perovskite quantum dot solar cells

Here, a pseudo-solution-phase ligand exchange (p-SPLE) strategy is developed for fabricating a CsPbI3 quantum dot (QD) solar cell. Using short organic aromatic ligands to partly replace the long-chain ligands in a QD solution, the p-SPLE treated CsPbI3 QD solar cell had an enhanced power conversion efficiency of up to 14.65% together with improved stability.

Highly Efficient and Air-Stable Heterostructured Perovskite Quantum Dot Solar Cells Using a Solid-State Cation-Exchange Reaction

Perovskite quantum dots (PQDs) have expanded the scalability of perovskite materials by their high crystallinity, band-gap tunability, and surface ligand-driven functionalities in the colloidal state across optoelectronics as well as photovoltaics. To improve PQD performance in applications, however, defect control has emerged as a major challenge given the increased PQD surface area. Herein, we have developed a heterostructured PQD solar cell by combining CsPbI₃ and FAPbI₃ (FA, formamidinium) PQD layers to introduce a multinary PQD layer based on a solid-state A-site cation-exchange strategy. A heterostructure, including the solid-state diffusion-driven multinary PQD layer, creates an internally graded heterojunction for more efficient charge extraction. The best PQD cell achieves a power conversion efficiency (PCE) of 16.07% with negligible hysteresis. Furthermore, this architecture offers significantly enhanced stability with reduction of trap-assisted recombination as compared to cells of a monocompositional PQD layer. The unencapsulated device retains a 96% PCE after 1000 h in ambient storage.

Red Light-Emitting Diodes with All-Inorganic CsPbI3/TOPO Composite Nanowires Color Conversion Films

This work presents a method for obtaining a color-converted red light source through a combination of a blue GaN light-emitting diode and a red fluorescent color conversion film of a perovskite CsPbI3/TOPO composite. High-quality CsPbI3 quantum dots (QDs) were prepared using the hot-injection method. The colloidal QD solutions were mixed with different ratios of trioctylphosphine oxide (TOPO) to form nanowires. The color conversion films prepared by the mixed ultraviolet resin and colloidal solutions were coated on blue LEDs. The optical and electrical properties of the devices were measured and analyzed at an injection current of 50 mA; it was observed that the strongest red light intensity was 93.1 cd/m2 and the external quantum efficiency was 5.7% at a wavelength of approximately 708 nm when CsPbI3/TOPO was 1:0.35.

Photo-Induced Black Phase Stabilization of CsPbI3 QDs Films

α-CsPbI3 quantum dots (QDs) show outstanding photoelectrical properties that had been harnessed in the fabrication of perovskite QDs solar cells. Nevertheless, the stabilization of the CsPbI3 perovskite cubic phase remains a challenge due to its own thermodynamic and the presence of surface defects. Herein, we report the optimization of the CsPbI3 QDs solar cells, by monitoring the structure, the morphology and the optoelectronic properties after a precise treatment, consisting of the conventional solvent washing with a time limited ultraviolet (UV) exposure combination, during the layer-by-layer deposition. The UV treatment compensates the defects coming from the essential but deleterious washing treatment. The material is stable for 200 h and the PCE improved by the 25% compared with that of the device without UV treatment. The photo-enhanced ion mobility mechanism is discussed as the main process for the CsPbI3 QDs and solar cell stability.