Herein, we designed and synthesized an ether chain functionalized fullerene derivatives [
6,
6]-phenyl-C
61-butyricacid-(3,5-bis(2-(2-ethoxyethoxy)ethoxy)phenyl)methyl ester (C
60-2EPM) and applied as a modification layer on ZnO cathode buffer layer (CBL) in inverted OSCs devices. The inverted devices composed of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno [3,4-b]thiophene-)-2-carboxylate-2-6-diyl)] (PTB7-Th):[
6,
6]-phenyl-C
71-butyric acid methyl ester (PC
71BM) showed better device performance by using the ZnO/ fullerene derivatives electron transport layer formed by one-step spin-coating technique than control device. When fullerene derivatives with ions groups (such as sulfonate, ammonium, phosphate) spin-coated on ZnO, the ions may incorporate in photovoltaic layer and decrease the lifetime of primary exciton, which can be explained by the formation of charge-transfer states that stabilized by the coulomb field of ions [
36]. However, the application of ether chain functionalized fullerene derivatives C
60-2EPM may avoid the phenomenon of ions migration, and guarantee the lifetime and stability of device. The fullerene derivatives C
60-2EPM have selected solubility and can support mutil-layer OSCs structures by solutions processing. The existence of large amount of fullerene derivatives in cathode interface layer were expected to form a multi transporting channels for electrons and decrease the hole quenching at the cathode for the polymer: fullerene solar cells (Fig. 1). With two concentrations (2.0 and 4.0 mg/mL) of C
60-2EPM applied in inverted OSCs with structure of ITO/ZnO/fullerene derivative/PTB7-Th:PC
71BM/MoO
3/Al, it was found that the PCE of the devices could be obvious enhanced to 8.38% and 8.65% compared with 8.11% of bare ZnO. The C
60-2EPM was also used as an additive in poly (3-hexylthiophene) (P3HT):phenyl-C
61-buty-ric acid methyl ester (PC
61BM) system to form a ternary system, the devices with 5%, 10%, 15% and 20% additions of C
60-2EPM have got PCEs of 3.64%, 3.84%, 3.87% and 3.76% compared with the control device (PCE of 3.49%).