A. F. Gualdrón-Reyes, D. F. Macias-Pinilla, S. Masi, C. Echeverría-Arrondo, S. Agouram, V. Muñoz-Sanjosé, J. Rodríguez-Pereira, J. M. Macak and I. Mora-Seró
Engineering Sr-doping for enabling long-term stable FAPb1−xSrxI3 quantum dots with 100% photoluminescence quantum yield
J. Mater. Chem. C, 2021, 9, 1555
The Pb substitution in quantum dots (PQDs) with lesser toxic metals has been widely searched to be environmentally friendly, and be of comparable or improved performance compared to the lead-perovskite. However, the chemical nature of the lead substitute influences the incorporation mechanism into PQDs, which has not been explored in depth. In this work, we analyzed Sr-doping-induced changes in FAPbI3 perovskites by studying the optical, structural properties and chemical environment of FAPb1−xSrxI3 PQDs. The substitution of Pb by 7 at% Sr allows us to achieve FAPb1−xSrxI3 PQDs with 100% PLQY, high stability for 8 months under a relative humidity of 40–50%, and T80 = 6.5 months, one of the highest values reported for halide PQDs under air ambient conditions. FAPb0.93Sr0.07I3 PQDs also exhibit photobrightening under UV illumination for 12 h, recovering 100% PLQY at 15 days after synthesis. The suppression of structural defects mediated by Sr-doping decreases the non-radiative recombination mechanism. By attempting to increase the Sr content in PQDs, a mixture of 2D nanoplatelets/3D nanocubes has emerged, caused by a high Pb deficiency during the FAPb1−xSrxI3 synthesis. This contribution gives a novel insight to understand how the suitable/poor Pb substitution achieved through Sr-doping dictates the photophysical properties of PQDs that may be potentially applicable in optoelectronics.
S. Kahmann,O. Nazarenko,S. Shao, O. Hordiichuk, M. Kepenekian, J. Even, M. V. Kovalenko, G. R. Blake, M. A. Loi,
Negative Thermal Quenching in FASnI3 Perovskite Single Crystals and Thin Films
ACS Energy Lett. 5, 2512 (2020).
Formamidinium tin triiodide (FASnI3) is a strong contender for sustainable harvesting of solar energy and further optoelectronic applications. So far, only a few studies have considered its fundamental structure–property relationships, given the challenge of ensuring a high material quality. In a concerted effort, we here study high-quality FASnI3 single crystals through a combination of X-ray crystallography, density-functional-theory-based electronic structure calculations, and photoluminescence spectroscopy from room temperature down to 4K. The luminescence exhibits irregular trends upon cooling with a generally strong intensity increase, but a range of negative thermal quenching, leading to an intensity maximum around 185K which is absent in low-quality samples. Differences in the photoluminescence peak position and density-functional-theory-calculated band-gap energies highlight the importance of dynamic processes to the observable properties of FASnI3. The presented data offer deeper insight into the temperature-dependent characteristics of this halide perovskite and present opportunities for future exploration of its optoelectronic properties.
AFTER THE FIRST YEAR OF WORK SUBJECTED TO COVID CONSTRAINTS WE CAN HIGHLIGH THE FOLLOWING ACHIEVEMENTS:
* Synthesis of Rudorffites (Ag2BiI5 and Ag3BiI6) in the form of nanocrystals and films from molecular precursors.
* Synthesis of Cs4SnBr6 & Sn-doped CsBr nanoparticles
* Successful synthesis of FASnI3 polycrystalline thin films from molecular precursors and fabrication of solar cells.
* Ink development of noncommercial mixed metal oxides as inorganic Hole / Electron Transport Layers (HTL/ETLs).
* PHOTONICS: Successful demonstration of ASE and LASING in FASnI3 thin films.
DROP-IT has received funding from the European Union’s Horizon 2020 FET-OPEN research programme under grant agreement No 862656.