Meysam Gharahcheshmeh, Massachusetts Institute of Technology
Electrical Conductivity and Optical Transparency Characteristics of oCVD PEDOT Films Using VOCl3 Oxidant
Written by Bharati Neelamraju
Organic chemical vapor deposition (OCVD) is a variant of the classical CVD techniques for organic materials. Meysam Gharahcheshmeh presented the work done in the Karen Gleason group at the Massachusetts Institute of Technology. The researchers used this technique for deposition of a conducting polymer called PEDOT which can be used as a hole transport layer (HTL) in perovskite photovoltaic devices. Its solution processable counter part is PEDOT:PSS which is acidic in nature and creates known interface issues. Gharahcheshmeh walked us through the differences in the charge transport properties of solution processed PEDOT:PSS and OCVD PEDOT on its own and as a HTL in a device geometry. He showed the control that OCVD has on molecule orientation which can be varied from face on to edge on by changing the substrate temperatures. He also gave details about using a liquid oxidant versus a solid oxidant for the process of OCVD and how the use of two different sources affects the deposited layer characteristics. He concluded his talk by showing how OCVD PEDOT is in fact more stable with time in a perovskite device compared to PEDOT PSS as a hole transport layer.