PANDA: a self-driving lab for studying electrodeposited polymer films

We introduce the polymer analysis and discovery array (PANDA), an automated system for high-throughput electrodeposition and functional characterization of polymer films. The PANDA is a custom, modular, and low-cost system based on a CNC gantry that we have modified to include a syringe pump, potentiostat, and camera with a telecentric lens. This system can perform fluid handling, electrochemistry, and transmission optical measurements on samples in custom 96-well plates that feature transparent and conducting bottoms. We begin by validating this platform through a series of control fluid handling and electrochemistry experiments to quantify the repeatability, lack of cross-contamination, and accuracy of the system. As a proof-of-concept experimental campaign to study the functional properties of a model polymer film, we optimize the electrochromic switching of electrodeposited poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films. In particular, we explore the monomer concentration, deposition time, and deposition voltage using an array of experiments selected by Latin hypercube sampling. Subsequently, we run an active learning campaign based upon Bayesian optimization to find the processing conditions that lead to the highest electrochromic switching of PEDOT:PSS. This self-driving lab integrates optical and electrochemical characterization to constitute a novel, automated approach for studying functional polymer films.

Fabrication and Performance Evaluation of a Nanostructured ZnO-Based Solid-State Electrochromic Device

In this study, we present an all-solid-state electrochromic device (ECD) that eliminates the need for hard-to-obtain materials and conventional liquid/gel electrolytes. Using a cost-effective and industrially scalable spray coating technique, we developed an ECD containing a layer of zinc oxide nanorods (ZnOnano) synthesized via a simple solochemical route. The device configuration includes a preformed Al-coated glass substrate, acting as a counter electrode, within a glass/Al/ZnOnano/PEDOT:PSS architecture. The device exhibits reversible switching between light blue and dark blue states upon application of -1.2 V and +2.8 V, respectively, with a significant difference in transmittance between bleached and colored states in the visible-NIR spectrum, featuring a high coloration efficiency of 275.62 cm2/C at 600 nm. The response times required for both coloring and bleaching states were 9.92 s and 7.51 s, respectively, for a sample with an active area of 5.5 × 2.5 cm2. Regarding the electrochemical stability of the ZnO-based ECD, the transmittance modulation reached around 8.01% at 600 nm after 12,800 s, following initial variations observed during the first 10 cycles. These results represent significant progress in electrochromic technology, offering a sustainable and efficient alternative to traditional ECDs. The use of economical fabrication techniques and the exclusion of critical materials highlight the potential for widespread industrial adoption of this novel ECD design.

Influences of solvents and monomer concentrations on the electrochemical performance and structural properties of electrodeposited PEDOT films: a comparative study in water and acetonitrile

Poly(3,4-ethylenedioxythiophene) (PEDOT) has emerged as a promising coating for neural electrodes especially through convenient electrodeposition methods. To investigate the influences of solvents and EDOT monomer concentrations on the electrochemical performance and structural characteristics of PEDOT, both aqueous and acetonitrile solutions were employed with varying monomer concentrations during deposition. The prepared PEDOT films were examined for the surface morphology, electrochemical performance, and chemical structures. The results showed that an increase in EDOT concentration in either solvent led to PEDOT films with improved charge storage capacity and reduced impedance magnitude. At equivalent monomer concentrations, PEDOT films generated in acetonitrile exhibited a rougher surface texture and better electrochemical performance. Notably, the growth rate of charge storage capacity of PEDOT prepared in acetonitrile relative to the deposited charge density was 2.5 times that of PEDOT prepared in water. These findings could help to the optimization of PEDOT coating preparation to enhance electrode performance.