A Method for Rapid Screening of Photosensitizers by Scanning Electrochemical Microscopy (SECM) and the Synthesis and Testing of a Porphyrin Sensitizer

A picoliter solution dispenser was used to fabric-ate photosensitizer arrays on mesoporous TiO2 electrodes. The scanning electrochemical microscopy (SECM) technique, modified by replacing the usual ultramicroelectrode (UME) with an optical fiber and using the photooxidation of iodide in acetonitrile in a photoelectrochemical (PEC) cell, was shown to be useful for the initial screening of potential PEC photosensitizers. This SECM technique allows for the rapid identification of new dyes and also can be used to investigate the synergetic effect of multiple dyes for application in dye-sensitized solar cells (DSSCs). This technique was specifically demonstrated via the synthesis and analysis of a new, bis-bithiophene functionalized porphyrin derivative, wherein the modified SECM technique was used to carry out an initial test of its PEC efficiency relative to other dyes. The PEC properties of bulk films based on this new porphyrin derivative were then investigated and the results shown to be in good agreement with those obtained using the SECM method.