Since a few years, the perovskite solar cells (PSCs) have emerged as a new technology for next-generation photovoltaics. These materials, as exemplified by the archetypal methyl-ammonium lead tri-iodide (CH3NH3)PbI3 (MAPI), have several key advantages: PSCs can be prepared using solution processing at temperature not exceeding 150°C, and their power conversion efficiencies (PCE) reach over 22%. However, PSCs have two main drawbacks: they contain the toxic lead element, and they exhibit chemical instabilities to moisture, oxygen, light, etc.
In this context, the central goal of the MORELESS project is to develop new materials belonging to the family of halide perovskites, suitable for light absorption in PV devices and offering improved stability (“MORE stable” than MAPI) while alleviating the most troubling issue of toxicity (“LESS lead” than MAPI). MORELESS will implement two different strategies. The first strategy consists in the search for lead deficient HPs materials (d-HPs). This new type of hybrid perovskites, (A,A’)1+xPb1-xI3-x (A, A’, organic monocations), discovered recently by the PI, contains less lead while keeping a 3D architecture, is more stable than MAPI and offers increased flexibility of its chemical composition. We propose to focus on this new type of hybrid perovskite by preparing new materials through substitutions on the A, A’, Pb and I sites. MORELESS also aims at discovering new kinds of d-HPs materials. The second strategy seeks for lead-free materials based on iodobismuthate or iodoantimonate networks. These materials are known to be stable and easily prepared as thin films. While non-perovskite compounds have been mainly used for PSCs applications, we propose to focus on 1D and 2D perovskite networks (corner-sharing octahedra) based materials. The next targets will be stabilization of 3D perovskite NMI3 (M= Bi3+/Sb3+), using neutral molecule N, consistently with recent predictions, as well as monovalent cation such as Ag+ in order to stabilize bismuth(antimony)-rich M3+/Ag+ perovskite networks. Once interesting materials will be obtained and characterized (X-ray, NMR, and others), thin films will be prepared to afford well-crystallized, fully covering, efficient light absorbing and adherent thin films. These layers will be characterized by XRD, SEM, EDX, AFM and XPS. Then the PSCs will be prepared and the cell performances determined for the various new perovskites (e.g., J-V curve measurements and impedance spectroscopy). For the best materials, other full studies will be carried out, particularly the aging of the layers will be followed by several techniques. First principles calculations and modeling will be performed both to support the interpretation of available experimental findings, including NMR data, and provide guidance to determine the choice of the next synthetic targets. Available structural data will allow investigation of electronic and optical properties in relation with experimental outcomes and DFT methods will provide complementary insight for foreseen atomic substitutions.
MORELESS is a collaborative project between partners having experience in the field of HPs and a strong expertise in complementary fields that are essential for successful outcome. This multidisciplinary project includes chemistry of materials (task 1), preparation and characterizations of PSCs (task 2) and modeling (task 3). At Moltech-Anjou (Angers, partner 1), the design, and the preparation of materials as well as X-ray characterizations will be assumed by N. Mercier, the coordinator of the project. At the IMMM institute (Le Mans, partner 2), the solid state NMR characterization of materials will be performed by J. Dittmer. In the MPOE-IRCP group of T. Pauporté (Chimie ParisTech, partner 3), material shaping, notably the electrical and optical characterizations and solar cell measurements and aging issue will be carried out. At ISCR (Partner 4) C. Katan will coordinate the theoretical work.
MOLTECH-Anjou (Divers public)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
INSTITUT DES SCIENCES CHIMIQUES DE RENNES
Institut de Recherche de Chimie Paris
INSTITUT DES MOLÉCULES ET MATÉRIAUX DU MANS
Help of the ANR 505,440 euros
Beginning and duration of the scientific project: December 2018 - 42 Months