An approach for an advanced anode interfacial layer with electron-blocking ability to achieve high-efficiency organic photovoltaics

The interfacial properties of PEDOT:PSS, pristine r-GO, and r-GO with sulfonic acid (SR-GO) in organic photovoltaic are investigated to elucidate electronblocking property of PEDOT:PSS anode interfacial layer (AIL), and to explore the possibility of r-GO as electronblocking layers. The SR-GO results in an optimized power conversion efficiency of 7.54% for PTB7-th:PC₇₁BM and 5.64% for P3HT:IC₆₁BA systems. By combining analyses of capacitance-voltage and photovoltaic-parameters dependence on light intensity, it is found that recombination process at SRGO/active film is minimized. In contrast, the devices using r-GO without sulfonic acid show trap-assisted recombination. The enhanced electron-blocking properties in PEDOT:PSS and SR-GO AILs can be attributed to surface dipoles at AIL/acceptor. Thus, for electron-blocking, the AIL/acceptor interface should be importantly considered in OPVs. Also, by simply introducing sulfonic acid unit on r-GO, excellent contact selectivity can be realized in OPVs. (Graph Presented).