American Association for Aerosol Research - Abstract Submission

AAAR 36th Annual Conference
October 16 - October 20, 2017
Raleigh Convention Center
Raleigh, North Carolina, USA

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Aerosol Routes to Fabricate Stable Perovskite Solar Cells under Ambient Conditions

SHALINEE KAVADIYA, Pratim Biswas, Washington University in St. Louis

     Abstract Number: 796
     Working Group: Nanoparticles and Materials Synthesis

Abstract
Perovskite (CH3NH3PbI3) solar cells have huge potential to be the future photovoltaic technology in the market, due to the rapid rise in their efficiency and low processing costs. Despite their high efficiency, the instability of perovskite material is a hindrance in their commercialization. Perovskites readily degrades in the presence of moisture. Thus, most of the studies are performed in a controlled humidity environment. In this work, we use a simple and scalable aerosol-based technique, electrohydrodynamic atomization (Electrospray in short) to make stable perovskite solar cells under ambient condition1. A two-step deposition method is used to form the perovskite layer, where PbI2 is spin coated and CH3NH3I (MAI) is electro-sprayed on the PbI2 layer at room temperature. Both the precursors react on the surface and form perovskite (CH3NH3PbI3). We then optimize the process parameters, namely, electrospray deposition time, MAI concentration, substrate-to-nozzle distance, and flow rate (droplet size) to make efficient solar cells.

Furthermore, the stability of the devices under ambient condition is tested for 5.5 months. The cells fabricated using the electrospray retain 75% of the initial efficiency on average. The key feature of the electrospray is controlling the reaction between the two precursors precisely, by gradually supplying MAI nanoparticles onto the PbI2 layer. The controlled reactivity leads to the formation of ultra-smooth and moisture-resistant perovskite film. After fabricating highly stable cell, we now aim to understand the effect of other parameters, namely, post-annealing of the electrosprayed perovskite film, deposition temperature, and electrospray polarity. An interesting phenomenon of intermediate perovskite phase formation occurs during the electrospray-assisted fabrication, which then vanishes after annealing at high temperature. Another important point to note here is that the type of ions generated from electrospray changes with the changes in electrospray polarity and affect the perovskite formation reaction. We performed in-situ Grazing Incidence Wide Angle X-ray Scattering (GIWAXS) at Synchrotron Facility, Advanced Photon Source at Argonne National Laboratory to understand the phase transition and perovskite formation reaction in electrospray. We will present the aerosol-assisted fabrication of stable perovskite solar cells and some interesting fundamental results from in-situ electrospray-GIWAXS measurement.

1. Kavadiya et al., Electrospray-assisted fabrication of efficient and highly stable perovskite solar cells at ambient conditions, Advanced Energy Materials, doi: 10.1002/aenm.201700210, 2017.