Definizione di nuove strategie per la crescita di perovskiti ibride ad alta stabilità e tempo di vita attraverso ingegneria atomistica della struttura reticolare

Responsabili di progetto

Alessandra Alberti, Miyasaka Tsutomu

Accordo

GIAPPONE - JSPS - Japan Society for the Promotion of Science

Bando

CNR/JSPS biennio 2018-2019 2018-2019

Dipartimento

Scienze fisiche e tecnologie della materia

Area tematica

Scienze fisiche e tecnologie della materia

Stato del progetto

Nuovo

Proposta di ricerca

We intend to establish the bilateral project on the basis of the experience matured during the scientific collaboration between CNR-IMM in Catania (hereafter called It) and the Yokohama+Tokyo Universities (hereafter called Jp) that has been lasting since the 2013. It has given positive results culminated in 6 publications on scientific peer reviewed international journals, such as ACS Applied materials and interfaces (IF7.5) and Journal of Physical Chemistry C (IF4.5). Our collaboration has been ever promoted preparation of the perovskite materials (and solar cell devices) in Japan, and accurate analysis (and theoretical calculation) of degradation mechanism of pristine perovskite materials in Italy, separately; therefore, establishment of closer research system is required to accelerate the research on highly performing perovskites.
The Jp Principal Investigator, prof. T.Miyasaka, has the huge merit of being the first having substituted, in 2009, photo-active dyes with a film of special perovskite to efficiently produce photo-carriers in a hybrid architecture called PSC. This change has been still producing conveniences and allowing this cell efficiency to aim high. Starting from that date, an increasing emphasis have been dedicated to this new technology that provided Prof. T.Miyasaka with the title of PSC's father.
The collaboration will focus on 3-dimensional molecular design of new organo-halide-perovskite (APbX3, A+ = monocation and X- = halogens) crystals, based on a lattice structure engineering, for creation of high stability materials with competitive performances. Band structure, chemical and thermal stability, and carrier mobility of organic-lead halide perovskite can be modified by changing composition ratio of A-site cation and bridging halogen ions. Hybrid perovskites are required to be durable light absorber for multipurpose uses such as in photovoltaic, light sensing and light emitting devices. This subject is largely attracting the interest in the literature since, once stabilized, perovskites will have a disruptive role into the society. In this international framework and for the project purposes, Japanese University team in Japan will conduct preparation of new perovskite architectures with different molecular compositions by solution processing and will supply the samples to Italian team for advanced analyses. Japanese University team possesses state-of-the art equipment for perovskite preparation under highly controlled atmosphere with use of dry clean room and glove box.  Up to now, Japan team has achieved the best conversion efficiency of up to 22% on the mixed perovskite-based devices, which is comparably high with the world record efficiency of 22.1%, and using different composition of perovskite such as MAPbI3, FAPbI3, FA1-xMAxPb(I1-xBrx)3, FA1-xCsxPbI3, FA1-xCsxPb(I1-xBrx)3, and (FA1-xMAx)1-yCsyPb(I1-xBrx)3 and/or different device architectures, exceeding 20% efficiencies were successfully obtained. Based on this widely recognized experience, a plethora of materials will be thus explored with variability on both the A-site cations (e.g. FA+, MA+, Cs+) and the halogens (e.g. Br-, I-), because even 1% difference in the composition ratio significantly affects to carrier mobility and resulting device performances. In order to realize new perovskite like above, high level theoretical calculation, perovskite synthesis, accurate analyses, and reproducible device fabrication skill are required at same time. The Italian team will provide advanced characterization to investigate the lattice structure of the new architectures and the impact of temperature, atmospheric moisture, and light irradiation on their durability. The efforts are mostly devoted to the comprehension of the mechanisms governing the back-reaction of perovskites to the starting by-products that pilot the devices to failure. Since several variables are involved (temperature, water, oxygen, light illumination, UV, interfaces, texture, grain boundaries, etc.), simplified experimental conditions will be explored in order to try to discriminate the different contributions. X-ray Diffraction (XRD),X-Ray Reflectivity(XRR), High-Resolution TEM and STEM, Spectroscopic Ellipsometry(SE), all with in-situ characterization will be focused towards a deep comprehension of the phenomena occurring into the materials. Density Functional Theory (DFT)-based modeling of the perovskite lattice (defects,polymorphic transitions,etc) will provide crucial insights to define or refine growth and stabilization strategies.
As counterpart, Jp team will be engaged to prepare the theoretically indicated "new" perovskite, and apply the perovskite to solar cell device. At this stage, the prepared perovskite is provided to Italy team for accurate analysis of degradation process of the pristine perovskite based on experimental and theoretical studies.
Based on the result, Japan and Italy teams will compare the pure perovskite degradation with the deterioration of device performance from a view point of device durability, which involves not only inherent perovskite stability but also other factors such as reaction among metal oxide, organic hole transport layer (additives: pyridine,TFSI-,Li+ ions), light irradiation, electron and voltage stress, and degradation of HTL and/or HTL part independent on perovskite stability. Specifically, in Japan SEM (EDX), electronic impedance spectroscopy, laser beam induced current (LBIC) measurement, and 2-Dmapping of distribution of JSC, VOC and efficiency will be exploited to focus on the purposes.
The advanced perovskites, once optimised, will be integrated in device in Japan, and this step will close the loop with the experiment in Italy.
The past collaboration has given way to test mode of operation and approaches of the two parties, and it represents an important starting point that can enormously benefit from the possibility of exchanging people.

Obiettivi della ricerca

The collaboration aims at the design of new hybrid perovskite architectures with robust and stable lattice structure which would render the material reliable under operation. Thereby, highly efficient and durable perovskite solar cell will be realized. Device efficiency mainly relies to high-level carrier conduction and light absorption capability of the perovskite absorbing layers; their durability needs to counteract heat, moisture and light irradiation damages. To this intent, we move from elucidating the mechanism of degradation and atomistic changes in the perovskite lattice structures under different boundary conditions; we will extend the research from conventional materials (e.g. MAPbI3) to newly-designed perovskite structures. In the project, this basic research will be complemented with a proof of concept based on the integration of the new material in photovoltaic or other devices(e.g.LED)
We point out that the survey of new perovskites has been mostly attempting by brute-force way, which is a totally inefficient way. Instead, developing a highly reliable simulation of perovskite structure based on the experimental and theoretical investigations, prospect huge advantages.
The proposal moves from common experience (since2013) and is based on the complementarity of the two teams: the Japanese team expert in perovskite synthesis and advanced hybrid solar cells; the CNR team expert of in-depth investigations of the materials based by cutting-edge diagnostic techniques

Ultimo aggiornamento: 30/04/2024