Is It Possible to Achieve Antisolvent-free Mixed Cation Perovskite? Yes!
Manuel Felipe Vasquez a, Juan F. Montoya a, Daniel Ramirez a, Franklin Jaramillo a
a Centro de Investigación, Innovación y Desarrollo de Materiales – CIDEMAT, Universidad de Antioquia UdeA, Calle 70, 52-21, Medellín, Colombia
International Conference on Hybrid and Organic Photovoltaics
Proceedings of Online International Conference on Hybrid and Organic Photovoltaics (OnlineHOPV20)
Online, Spain, 2020 May 26th - 29th
Organizers: Tracey Clarke, James Durrant, Annamaria Petrozza and Trystan Watson
Poster, Manuel Felipe Vasquez, 072
Publication date: 22nd May 2020

Upscaling perovskite solar cell fabrication is one of the key challenges in the pathway to its industrialization. Frequently used solvents including DMSO or DMF present slow evaporation which difficulties the perovskite layer crystallization hindering their implementation in large scale deposition methods [1]. Alternatively, methylamine-based precursors have demonstrated rapid crystallization (< 1s), leading to uniform and specular films with enhanced optoelectronic properties[2–4]. These attributes have enabled efficiencies up to 19.6% by blade-coating [5] and mini-modules with 2000h of stability tested in outdoor conditions[6]. However, the methylamine-based solvent strategy has been focused on MAPbI3 perovskite and few efforts are reported in formamidinium based perovskites, limiting the path to more efficient and stable perovskites.

In this work, we study the requirements for stabilizing formamidinium perovskites using a methylamine based precursor. We found that the ratio of methylamine incorporated in the solution represent a crucial variable in the stabilization of alpha-phase perovskite. Initially, we found that at low methylamine ratios in solution, the films present mostly inactive 1D phases of FA3(MA)PbI5. This phase gradually disappears after increasing the amount of methylamine upon reaching an optimal ratio where only the alpha-phase is present. Fabricated devices using this protocol exhibit promising efficiencies up to 12%. Moreover, to gain insights into the molecular interactions behind this trend, we perform ATR-FTIR measurements. Interestingly, we found that the dipole interaction between methylamine and formamidinium cation directly determine the crystallization phases in the film. These results, open a window in the development and understanding of new precursors of efficiency and stability large scale perovskite devices.  

The authors gratefully acknowledge the financial support provided by the committee for the development of research (CODI) of the Univers idad de Antioquia, in the framework of the project 2017-16000. Also, the authors acknowledge the financial support of the Colombia Scientific Program within the framework of the call Ecosistema Cientifico (Contract FP44842-218-2018)

© Fundació Scito
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