Device Fabrication And Performance Optimization Of All-Polymer Solar Cells

All-polymer solar cells(all-PSCs)have excellent morphological stability of active layer to external factors,especially mechanical stress and thermal.compared with polymer donor and a small molecule(SM)acceptor polymer solar cells such as fullerene derivatives or n-type organic semiconductors(n-OSs).All-PSCs have recently attracted significant attention and become a hot research area in the field of new energy research and materials science.Howere,the power conversion efficiencies(PCEs)of the PSCs based on nonfullerene SM as acceptors were much higher than the all-PSCs.Herein,we developed high efficiency all-PSCs based on p-type conjugated polymer as donor and n-type conjugated polymer as acceptor,and further researched on the stability of the devices and the microstructure of the active layers.The main research results are as follows:1.All-PSCs based on n-type polymer as acceptor and p-type polymer as donor materials have attracted great attention due to their excellent device stability.However,a systematic study of thermal stability for all-PSCs has not been reported to date.Herein,we developed a high.efficiency and thermally stable all-PSCs based on a fluorinated wide bandgap polymer donor(PFBZ)and a narrow bandgap polymer acceptor(N2200).The PFBZ:N2200 pair shows complementary absorption spectra,matched energy levels and good blend morphology.As a result,the PFBZ:N2200-based devices under thermal annealing at 150? for 15 min achieved a high power coversion efficiency(PCE)of 8.1%with high open-circuit voltage of 0.90 V,short-circuit current density of 13.5 mA cm-2,fill factor of 67.0%as well as low energy loss of 0.56 eV.The efficiency of 8.1%was one of the highest values reported for the additive-free all-PSCs.When the thermal annealing time is extended to 180 min or the temperature is increased to 250?,the all-PSCs still retained a high PCE of over 7%.The results indicate that the PFBZ:N2200-based all-PSCs with high efficiency and excellent thermal stability are promising candidates for the practical applications of PSCs.2.In order to further improve the PCEs of the all-PSCs,we fabricated all-polymer all-PSCs based on a fluorinated wide-bandgap p-type conjugated polymer PM6 as donor,and a narrow bandgap n-type conjugated polymer PZ1 as acceptor.In addition to the complementary absorption and matching energy levels,the optimized blend films possess high cystallinity,predominantly face-on stacking,and a suitable phase separation.With this active layer,the device exhibited a high Voc of 0.96 V,a superior Jsc of 17.1 mA cm-2,a fine FF of 68.2%,and thus an excellent PCE of 11.2%,which is the highest value reported to date for a single-junction all-PSC.Furthermore,the devices showed good storage stability,after 80 days of storage in the N2-filled glovebox,the PCE still remained over 90%of the original value.Large-area devices(1.1 cm2)also demonstrated an outstanding performance with a PCE of 9.2%,among the highest values for the reported large-area all-PSCs.These results indicate that the PM6:PZ1 blend is suitable for roll to roll process.