Using microgels to control the morphology and optoelectronic properties of hybrid organic–inorganic perovskite films. Issue 44 (1st November 2018)

• Record Type: Journal Article
• Authors: Dokkhan, Chotiros; Mokhtar, Muhamad Z.; Chen, Qian; Saunders, Brian R.; Hodson, Nigel W.; Hamilton, Bruce
• Is Part Of: Physical chemistry chemical physics. Volume 20:Issue 44(2018)
• Page Start: 27959
• Page End: 27969
• Publication Date: 2018-11-01
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c8cp05148h
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Spin coating mixed microgel/perovskite precursor solutions gives disordered inverse opal perovskite films with morphologies and optoelectronic properties that are controlled by the microgel particles. Abstract : Microgels (MGs) are crosslinked polymer colloid particles that swell in a good solvent. Although MGs have been studied for over 80 years their ability to control the morphology and optoelectronic properties of composite films containing photoactive materials is in its infancy. Solution processable hybrid organic–inorganic perovskites such as CH3 NH3 PbI3− z Cl z have attracted enormous fundamental and applied interest because of their outstanding optoelectronic properties. There is considerable interest in establishing methods to control perovskite film morphology, for example, using micropatterning. Here, hydrophilic poly( N -vinylformamide)-based MGs were dispersed in perovskite precursor solution which was then spin coated to deposit CH3 NH3 PbI3− z Cl z /MG films for the first time. Remarkably, the CH3 NH3 PbI3− z Cl z /MG composites formed disordered inverse opal (DIO) films. The CH3 NH3 PbI3− z Cl z /MG composition ranges which gave DIO films are identified using a phase diagram. The pore wall thickness is shown to be controlled by the volume fraction of MGs used and a simple model is presented to explain this behaviour. The MGs not only caused CH3 NH3 PbI3− z Cl z to be more efficiently deposited but also increased light absorption and photoluminescence intensity. Demonstration solar cells constructed containing the DIO CH3 NH3 PbI3− z Cl z /MG films had an average conversion efficiency of 6.58 ± 0.81%. A mechanism for DIO film formation is discussed. The principles established in this study wherein MGs control the morphology and properties of CH3 NH3 PbI3− z Cl z /MG films should also apply to other perovskite/MG composites.