Alkylthio substituted thiophene modified benzodithiophene-based highly efficient photovoltaic small molecules

• Two new small molecules using alkylthiol flexible side chain to function BDTT based thiophene-conjugated were constructed.
• High performance with PCEs of over 8% for these two molecules based devices were obtained.
• DRSBDTT-BO based devices have better reproducibility than that of DRSBDTT-EH due to its good solubility in chloroform.

Two new small molecules, namely DRSBDTT-EH and DRSBDTT-BO, with alkylthio thienyl substituted benzodithiophene as the central unit and 3-ethylrhodanine as end groups, were designed and studied as the donors for solution processed organic solar cells. The optimized device based on DRSBDTT-EH bearing shorter alkylthio chain gave a power conversion efficiency (PCE) of 8.78%, which is slightly higher than that of device (8.53%) based on DRSBDTT-BO with longer alkylthio chain.

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