Aqueous-Processed Polymer/Nanocrystal Hybrid Solar Cells

With the consumption of the primary energy including coal,petroleum,natural gas,etc.,the human beings gradually recognize the necessity of developing continuable energy source.As one of the photoelectric conversion equipment which directly converse light into electricity,solar cells are developed first in 1954 by researchers and are considered to be one of the most popular candidates solving energy problems.The Si solar cells,which are the first-generation solar cells,reach power conversion efficiency?PCE?beyond 26%and possess good stability exceed 20 years.However,the defects are obviously including expensive,thick,inflexibility,etc.,which is adverse for the portable use.Though the second-generation solar cells such as CdTe,CIGS,etc.,have realized the property of light,the devices are still inflexible.Recent years,the third-generation solar cells,which are processed by solution method,have attracted extensive attentions.The development potential of the polymer solar cells,quantum dot solar cells,hybrid solar cells and perovskite solar cells is really great.Simultaneously,with the increasing of the world economy,the human beings pay much attention to the environment and health.It is definitely regulated that spraying carcinogenic toxic solvent is inhibited in some European countries.Therefore,it is significant to fabricate solar cells using clean solvent.In this paper,we try to combine the advantages of polymer?light,flexible?and nanocrystals?high mobility,broad absorption?to fabricate solar cells by using water as the solvent,the main three works are listed below:In the second chapter,we utilize the water-soluble insulating polymer polyvinyl alcohol?PVA?and CdTe nanocrystal as the photoactive materials and fabricate the photovoltaic devices.We systematically discuss the function of PVA.After introducing PVA into PPV:CdTe hybrid system,an enhanced photovoltaic performance is achieved.Besides,other insulating polymer such as chitosan and polyvinyl pyrrolidone are also tested and the functions are studied.Finally,we conclude the principle conditions of the insulating polymer.This is the first work which replaces conjugated polymer with insulating polymer for fabricating the polymer/nanocrystal hybrid solar cell,demonstrating the feasibility of replacing conjugated polymer.In the third chapter,we fabricate aqueous hybrid solar cells with single-side bulk heterojunction?BHJ?by using conjugated polymer PPV and CdTe nanocrystal.Through introducing three device structures,controlling the polymer content and changing the film thickness,we conclude the respective function of PPV and CdTe.After combining the advantages of PPV and CdTe,a single-side BHJ solar cell with PCE of 5.64%is achieved,this efficiency represents the highest values among aqueous-processed hybrid solar cells at that time.Moreover,we generalize this conclusion into PBTPV:CdHgTe hybrid solar cells which possess near-infrared contribution,an enhanced efficiency and near-infrared contribution are also achieved.In the fourth chapter,we fabricate aqueous hybrid solar cells with double-side BHJ by using conjugated polymer PPV and CdTe,Ti O₂ nanocrystals.Based on the third chapter,we construct a new BHJ and introduce it into the single-side BHJ device.The intensive studies reveal that the carrier extraction efficiency,quantum efficiency,width of depletion region and carrier lifetime is improved.The PCE of the double-side BHJ device reaches 6.01%,which breaks 6%among aqueous-processed solar cells.Furthermore,we replace TiO₂ with ZnO and obtain an efficiency of 6.5%,this result further confirms the superiority of this device structure.In conclusion,we successfully obtain polymer/nanocrystal hybrid photovoltaic devices by using water as solvent.The introduction of polymer and nanocrystal ensure the flexibility and efficiency of the device.The use of water as solvent guarantees the future industrial large-area production.This paper not only makes the fundamental research,but also aims at the industrial production.