Influence of Chloride/Iodide Ratio in MAPbI_3-xCl_x Perovskite Solar Devices: Case of Low Temperature Processable AZO Sub-Layer

• Published in: Energies
• Main Authors: Manon Spalla, Lara Perrin, Emilie Planès, Muriel Matheron, Solenn Berson, Lionel Flandin
• Format: Article
• Language: English
• Published: MDPI AG 2020-04-01
• Subjects: chloride/iodide ratio; low temperature processable AZO; MAPbI_3-xCl_x perovskite
• Online Access: https://www.mdpi.com/1996-1073/13/8/1927

A significant current challenge for perovskite solar technology is succeeding in designing devices all by low temperature processes. This could help for both rigid devices industrialisation and flexible devices development. The depositions of nanoparticles from colloidal suspensions consequently emerge as attractive approaches, especially due to their potential for low temperature curing not only for the photoactive perovskite layer but also for charge transporting layers. Here, NIP solar cells based on aluminium doped zinc oxide (AZO) electron transport layer were fabricated using a low temperature compatible process for AZO deposition. For the extensively studied perovskites based on methylammonium lead halides (MAPbI_3-xCl_x), the chloride/iodide equation is widely proposed to follow an optimal value corresponding to an introduced MAI:PbCl₂ ratio of 3:1. However, the perovskite formulation should be considered as a key parameter for the optimization of power conversion efficiency when exploring new perovskite sub-layers. We here propose a systematic method for the structural determination of the optimal ratio. It may depend on the sublayer and results from structural changes around the optimal value. The functional properties gradually increase with the addition of chlorine as long as it remains intercalated in a single phase. Above the optimal ratio, the appearance of two phases degrades the system.