An alcohol-soluble titanium chelate,T itanium (IV) oxide bis(2,4-pentanedionate) (TOPD),is used as electron collectio n layer instead of the low-work-function metal Ca to improve the stability of polymer solar cells (PSCs),where poly(3-hexylthiophene) (P3HT) and fullerene de rivatives (PC₆₀BM or PC₇₀BM) are used as donor and acceptor material s.The TOPD film was prepared by spin-coating TOPD isopropanol solut ion on the photoactive layer,and then annealing it in air at 60℃ for 15min.By optimizing the thickne ss of TOPD layer and the device fabrication process,the Jsc of the PSCs can be significantly improved.By introducing TOPD as electron collection layer,the PCE of the P3HT:PC60BM-based PSCs can be enhance d from 2.72% to 3.65% under the illumination of AM1.5G,100mW·cm－2.When using PC₇₀ BM instead of PC₆₀BM as donor,the PCE of the device can be further improved to 3.96%.The improvement i n device performance can be mainly attributed to the enhancement in electron mob ility and the decre ase in the series resistance of the device upon insertion of TOPD buffer layer .In addition,PSCs with the TOPD cathode buffer layer exhibit a much higher stabi lity and longer lifetime compared with the devices using Ca as cathode.The resul ts indicate that the TOPD is a promising electron collection layer for PSCs.