Effects of Background Pressure During Resonant Infrared Matrix-Assisted Pulsed Laser Evaporation (RIR-MAPLE) Deposition of Thin Film Hybrid Perovskites

Student’s name: Elise Jantz Home Institution: Goshen College NNCI Site: RT-NN @ Duke REU Principal Investigator: Dr. Adrienne Stiff-Roberts - University Program in Materials Science and Engineering, Duke University REU Mentor: Joshua Ayeni - University Program in Materials Science and Engineering, Duke University Abstract: Hybrid organic-inorganic perovskites (HOIPs) are a class of materials with highly tunable electrical properties that are excellent candidates for novel optoelectronic technologies such as photovoltaics and light emitting diodes. Resonant Infrared Matrix-Assisted Pulsed Laser Evaporation (RIR-MAPLE) is a physical vapor deposition technique that reduces the limitations of traditional solution processing methods. During RIR-MAPLE deposition, the frozen precursor solution is placed in the vacuum chamber, where the hydroxyl bonds of the matrix solvent resonantly absorb energy from the laser, producing a vapor plume that propels the desired precursor materials up to the substrate. However, previous studies of RIR-MAPLE deposition for HOIPs have been conducted under active vacuum conditions, which are a substantial obstacle to the use of RIR-MAPLE for HOIP manufacturing on an industrial scale. Samples of 2D [phenylethylene lead iodide, (PEA)2PbI4] and 3D [methyl ammonium lead iodide, MAPbI3] HOIPs were grown at pressures from 10-5 mTorr to 500 mTorr and were analyzed using atomic force microscopy and optical spectroscopy methods. Photoluminescence (PL) spectroscopy indicated a correlation between background pressure (BGP) during deposition and photoluminescence peaks, where films grown at higher pressures had narrower, blue-shifted peaks. This suggests that films grown at higher BGP have fewer defects that cause PL peak widening. In addition, atomic force microscopy showed that while an increase of BGP from 10-5 mTorr to 100 mTorr was associated with an increase in film roughness of approximately 60%, further increase of BGP up to 500 mTorr did not significantly affect film roughness. These results show that HOIP films of comparable quality can be produced under higher BGP, demonstrating the continuing potential of RIR-MAPLE as a large-scale HOIP deposition technique.