Efficient dual cathode interfacial layer for high performance organic and perovskite solar cells

Cathode interfacial layer (CIL), phenylquinoline-based, 10-ethyl-3,7-bis(4-phenylquinolin-2-yl)-10H-phenothiazine (PTDPQ) was employed between the ZnO and photoactive layer, poly[4,8-bis[(2-ethylhexyl)oxy] benzo[1,2-b:4,5-b'] dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl) carbonyl] thieno[3,4-b]-thiophenediyl] (PTB7):[6,6]-phenyl C-71-butyric acid methyl ester (PC71BM) for the inverted organic solar cells (IOSCs) and between LiF and PTB7: PC71BM for conventional organic solar cells (COSCs). It was also incorporated as interfacial layer in perovskite solar cells (PSCs). For the ZnO/PTDPQ bilayer, the power conversion efficiency (PCE) enhanced to 8.69%, which is about 15% improvement than that of the control IOSCs reference device. For the PTDPQ/LiF bilayer, it was achieved to 8.06%, and after insertion of PTDPQ as interfacial layer for PSCs, average PCE enhanced to 16.45% from that of 15.28% reference device. Hereinafter, PTDPQ as CIL enhances the solar cells device performance. It is analyzed that the charge recombination is suppressed and facilitates charge extraction due to the incorporation of the dual CIL as accordance with observed improvement of the solar cell parameters. The devices with dual CIL showed the higher electron mobility which matches with the higher fill factor and improved current density. The dual CIL exhibited excellent impact on enhancing the photovoltaic properties of OSCs and PSCs along with long-term stability.