Experimental investigation of the mechanical robustness of a commercial module and membrane-printed functional layers for flexible organic solar cells

A coupled mechanical and electrical characterization method to monitor the correlation of organic photovoltaic (OPV) electrode resistance and cell performance upon tensile strain and to verify the cause of deterioration and the effect of OPV performance under tensile stress has been developed. Both a commercial OPV module and ethylene tetrafluoroethylene (ETFE) membrane-printed OPV electrode layers have been tested by applying the method. The encapsulation layer strength has been found to be the mechanical bottleneck of the tested commercial OPV module. The decrease in the transparent electrode conductance has been found to be responsible for cell degradation upon tensile strain, with the threshold tensile strain at approximately 2%. A test results comparison between ETFE- and polyethylene terephthalate (PET)-printed OPV layers demonstrated that ETFE-printed electrodes are less brittle and sensitive to tensile strain owing to the network pattern response of ETFE-printed electrodes. In addition, the adoption of Ag/poly(3,4-ethylenedioxythiophene) (PEDOT) layering can improve the tensile strain threshold to almost double to maintaining 80% of the initial normalized layer conductance through the advantage of its “bridging effect”. Collectively, our results provide valuable information and illustrate a promising future for architectural membrane printed OPV.