| The organic-inorganic hybrid perovskite APb I3（A=Methylamine,Formamidine）is a cubic crystal structure formed through embedding A-site organic cations into inorganic[Pb I6]4-octahedral interstice,which has emerged as an ideal material for low-cost and high-efficiency photovoltaic applications in the future and therefore attracted extensive attention in recent years.In a variety of perovskite device structures,the fully-printable perovskite solar cell（f-PPSC）based on triple mesoscopic（Ti O2/Zr O2/carbon）structure abandons the high-cost organic hole transport materials and shows the advantages of commercial application in material use,preparation process and device stability,but its efficiency still needs to be further improved.In the f-PPSC device structure,the thick mesoscopic films and the absence of hole transport layer pose a challenge to perovskite filling and crystallization,carrier transport and separation,which limits the further improvement of open circuit voltage(Voc)and fill factor（FF）.Herein,this dissertation focuses on the optimization of perovskite light absorbing materials,mesoporous electrode materials and interface passivation,which play a decisive role in the device performance.By improving the electrode performance,adjusting the interface energy level,passivating defects and optimizing perovskite components,the efficiency and stability of f-PPSC devices are improved.Simultaneously,the physical mechanisms of enhanced Voc and FF by interface charge transfer,interface energy level matching and interface defect passivation are revealed.The main research contents and results of the thesis are as follows:（1）Due to the absence of hole transport layer for f-PPSC devices,the performance of carbon electrode directly affects the extraction and transmission of holes.By introducing liquid metal（Galinstan,Ga In Sn）,the contact performance of the carbon electrode was improved.Thanks to the high conductivity and the fluidity at room temperature of the liquid metal,the square resistance of the carbon electrode was effectively reduced.More importantly,the liquid metal has a high density and eventually tends to exist at the bottom of the carbon electrode,effectively filling the gap between the carbon electrode and Zr O2,adding channels for the effective extraction and transmission of holes and improving the charge transfer ability of the interface.Thus,the series resistance of the whole device was reduced,and the optimized device obtained 13.51%power conversion efficiency（PCE）.（2）To solve the problem of large Voc loss in f-PPSC devices,we prepared a gradient bilayered zinc tin oxide（ZTO）films and used as the dense layer.The electron mobility and energy level structure of ZTO thin film can be regulated by adjusting the ratio of Zn and Sn.When the Zn/Sn ratio is 3 and 1,the electron mobility of 3.79 and 4.27 cm2 V-1s-1 were obtained respectively.Due to the appropriate band alignment,the built-in electric field of the device was enhanced.Furthermore,the improved electron mobility promoted the carrier’s extraction and transmission,effectively reduced the interface recombination rate,increased the Voc of the device to 1.02 V,and obtained PCE is 15.86%.（3）A novel bifacial passivation strategy for f-PPSC was proposed through post-treatment the triple mesoscopic films using monoethanolamine（MEA）.The results showed that the hydroxyl ligand in MEA molecule can interact with Ti O2 surface through hydrogen bond,leading to reduced oxygen vacancy defects on Ti O2 surface and reduced energy barrier between perovskite and Ti O2,so as to improve electron transfer efficiency.Besides,the amino group in MEA acts as Lewis base to passivate Pb defects in perovskite materials,the density of states of perovskite surface defects was reduced,resulting in the increase of built-in electric field.Based on the double functional groups of MEA molecules,the simultaneous passivation of Ti O2 surface defects and perovskite surface defects was effectively realized,and the Voc and FF of the device were improved.At the same time,the defect healing and screen effect of MEA passivation layer significantly improve the optical stability of the device.（4）Dimethylammonium（DMA）cations were introduced into the precursor solution of Cs doped FAPb I3 perovskite(Cs0.12FA0.88Pb I3).The results showed that when the molar ratio of DMA addition is 0.03,a small amount of DMA is doped into the perovskite lattices,meanwhile,an intermediate compound DMAPb I3 is formed and exists at grain boundaries,which improves the crystallinity of perovskite films and reduces nonradiative recombination through a passivation role.With these benefits,the best-performing f-PPSC device attained a PCE of 17.46%with favorable stability. |
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