We report the high efficacy of p-doping of conjugated polymers using the HOMO-SOMO(HOMO)-doping process involving multi cation salts capable of accepting more than one electron per dopant. In this concept, one can rediuce the molar dopant ratio radically and still achieve appreciably good charge carrier density and high conductivity for low degrees of doping below 5 mol%. The main credit goes to Gert and Adrian ! See Macromolecular Rapid Communications, 2021, 42, 2100443; https://doi.org/10.1002/marc.202100443
A comprehensive investigation of four polydiketopyrrolopyrroles (PDPPs) with increasing ethylene glycol (EG) content and varying nature of comonomer is studied, and guidelines for the design of efficient mixed ion‐electron conductors (MIECs) are published in Adv. Funct. mater. 2021. A considerable cycling stability for 1200 cycles and an outstanding cell compatibility render these PDPPs as viable candidates for in vitro and in vivo bioelectronics.
We reported in Adv. Mater. 2020, a new doping strategy by mixing a hole conductor having partly filled HOMO and a conjugated polymer having fully occupied HOMO resulting in a HOMO-HOMO electron transfer. This was a joint research work with the Pflaum group of University of Würzburg. This concept opens new routes to dope p-type organic semiconductors to obtain highly stable doped systems. It also does not require any acceptor dopant molecule such as a fluorinated TCNQ derivative having low lying LUMO values.
Congrats Philip and his team! Philip, Jonas, Adrian and Florian have established a measurement setup for electrochemical transistors at AFUPO in our research building PNS. This setup is long overdue and allows us to study diverse mixed ion-electron conductor materials available in our research group.
Three new Master students, - Julian Hungenberg and Linus Hager (Bioelectronics) and Lukas Conrad Hennerici (Cathode Materials for Batteries) - joined AFUPO in June 2020. Welcome to AFUPO family.
Our research group has adapted to the constraints of the COVID-19 pandemic and all research students and Masters have returned stepwise and are working now regularly in the lab. Some are finishing their pending papers or thesis. We also have regular research seminars and literature discussion meetings in Zoom/Skype every week. I take this opportunity to thank all my group members for having the patience and understanding the situation and managing things efficiently in an extraordinary time. We hope to sit together and discuss things in person soon. We also wish all our research partners within and outside Germany healthy days, weeks and months.
Jannik (Batteries), Adrian (Perovskites and EIS) and Andreas (Block copolymers and Alignment) finished their Master thesis and joined as new PhDs in 2020 to strenghen the activities of AFUPO family. Congrats and looking forward towards new impulses and ideas!
In a joint research work within BayBATT, we published detailed DRT analysis of Nyquist plots obtained from Electrochemical Impedance Spectroscopy of solid electrolytes to understand the bulk as well as interface impedance as a function of the nature of electrolytes varying from single-ion conductor polymer to polymer bottle brushes and ceramic electrolytes, all of which are interesting candidates for a solvent-free Li-metal anode battery
In a perspective article in Macromolecules, the challenges and opportunities of polymeric thermoelectrics for medium temperature and low power regime applications are reviewed. The main focus lies in the interconnectivities of the important TE parameters, Seebeck coefficient, thermal conductivity as well as electrical conductivity and how to improve both S and sigma simultaneously. A paradigm shift towards efficient doping at low dopant levels and separation of transport and fermi energy levels are strongly recommended.
Philip Schmode studied the concept of copolymerization as well as polar polythiophenes carrying oligoethyleneglycol substituents to obtain Ionic Electronic Mixed Conductors for applications in Organic Electrochemical Transistors. The corelation between chemical structures, volumetric capacitance, charge carrier mobility and µC* product are evluated in two papers published in Chem. Mater. (2019) and ACS AMI (2020).