1) Perovskite doping for the development of 4-level systems. Europium (III) and Yb (III) doping has been performed by means of direct substitutional doping or by intercalation of metal-organic lanthanide complexes. An innovative doping strategy was developed combining Eu(III) with naphtylmethylammonium as functional templating cation assisting the energy transfer from the perovskite to the lanthanide. Spectral tuning, enhancement of luminescence quantum yield and integration in light emitting devices have been achieved.
2) Impact of templating cations on lasing properties of layered perovskites. Tin perovskites have been developed as a viable lead-free platform, finding that they posses superior optical gain properties compared to the layered Pb-based counterparts. We observed that the templating cation plays a critical role in determining the crystallinity and defectivity of the material, in turn affecting the lasing characteristics. Upon proper synthetic design, we were able to demonstrate lasing in layered tin perovskites integrated with an optical resonator.
3) Effect of structural design on the optical gain of multidimensional perovskites. By combining the variable stripe-length (VSL) method and transient absorption, we have investigated the multi-excitonic interactions at high excitation densities and show that the modulation of the steric hindrance and fluorination of the templating cation plays a fundamental role on the optical gain properties, amplified spontaneous emission (ASE) threshold and operational stability. A dramatic impact is found on the optical gain coefficient, reaching a maximum of 1000 cm-1 in optimized compositions and showing a difference of two orders of magnitude depending on the templating cation, in turn affecting the carrier density at which ASE is observed.
4) Processing optimization of formamidinium (FA) and cesium-based lead perovskites and investigation of their structure-properties relationships. Despite showing excellent electroluminescence efficiency, FAPbI3 shows a high ASE threshold which hampers its implementation as coherent emitter. We found that the chemical composition plays a fundamental role to shape its optoelectronic properties, since the addition of bromine enhances the optical gain and improves the electroluminescence efficiency at high current densities, making it an excellent material for laser diodes. Beyond chemical composition, by using CsPbI3 nanocrystals as material platforms and modulating temperature and pressure, we have shown that crystal size and structural deformations have a deep impact on the optoelectronic properties of the material and must be taken into account for the educated design of these materials.
Scientific publications:
D. Cortecchia* et al, Layered perovskite doping with Eu3+ and -diketonate Eu3+ complex, Chem. Mater. 2021, 33, 2289−2297.
A. L. Alvarado-Leaños,D. Cortecchia* et al, Lasing in single-layered 2D tin perovskites, ACS NAno, Just Accepted,
https://doi.org/10.1021/acsnano.2c07705(odnośnik otworzy się w nowym oknie)O. Vukovic, A. Petrozza*, D. Cortecchia* et al, Structural effects on the luminescence properties of CsPbI3 nanocrystals, under submission.
C. Soci*, G. Adamo*, D. Cortecchia* et al, Roadmap on perovskite nanophotonics, under submission. (Invited Perspective in Optical Materials: X)
A. L. Alvarado-Leaños, D. Cortecchia et al, Optical gain of lead halide perovskites measured via the variable stripe length method: what we can learn and how to avoid pitfalls, Adv. Opt. Mater. 2021, 2001773.
G. Folpini, M. Palummo, D. Cortecchia et al, Band splitting and plurality of excitons in Ruddlesden-Popper metal halides, ChemRxiv. Cambridge: Cambridge Open Engage; 2021 (Under revision)
Conference presentations:
Synthetic design of metal halide perovskites for photonic applications, Small’s Energy Materials Virtual Symposium, 10 Nov 2020. (Invited Talk)
Low dimensional perovskites: from chemical design to photonic applications, Politecnico di Milano, 18 Feb 2022. (Invited Talk)
Amplified spontaneous emission in single-layerd 2D tin perovskites, MRS2022, Honolulu, May 23-25 2022. (Talk)
Single-layered 2D tin perovskites for lasing applications, Gordon Research Conference (GRC), Ventura, 12-17 Jun 2022. (Poster)
