| Perovskite solar cells(PSCs)have attracted extensive attention due to their excellent photoelectric performance over the years.The highest power conversion efficiency(PCE)has reached 25.5%rapidly,approaching the certificated efficiency of single crystal silicon solar cells,which makes PSCs one of the most potential new-generation photovoltaic technologies.Among various PSCs,printable mesoscopic perovskite solar cells(MPSCs)based on the mp-Ti O2/mp-Zr O2/carbon triple mesoscopic layer are of great potential for commercial applications due to their great advantages of low cost,easy upscaling and superior stability.However,the VOC loss in MPSCs is relatively larger than that in conventional PSCs,thus leading to a large PCE loss.This thesis focuses on improving the VOC and PCE of MPSCs through solvent engineering and additive engineering.Meanwhile,the application of new lead-free inorganic perovskite materials in MPSCs is also attempted in order to solve the toxicity and stability of organic-inorganic hybrid perovskite materials.The main research contents are as follows:(1)The effects of?-butyrolactone(GBL)homologues,such as?-pentanolactone,?-caprolactone,?-heptalactone and?-octanolactone,on the performance of perovskite solar cells were studied.?-valerolactone exhibits much higher solubility(1.2 M)of perovskite than GBL(0.8 M).In addition,the annealing temperature of printable MPSCs prepared by?-butyrolactone is generally 50°C,and?-valerolactone can still ensure the pore filling of perovskite in printable MPSCs when annealed at a higher temperature of 65°C.The mixed solvent of?-valerolactone and?-butyrolactone was further used to increase the solubility of perovskite,and the optimal device was obtained when the proportion of?-valerolactone was20%.The highest PCE of the optimal device prepared with mixed solvents is 14.37%,the VOC is 930 m V,the JSC is 23.95 m A/cm2,and the FF is 0.64.The results show that?-valerolactone provides more flexibility for preparing printable MPSCs.(2)Octyltrimethylammonium chloride(OTAC)was introduced as an additive to improve the performance of printable MSPCs.The influence of quaternary ammonium salts'side chain structure,chain length,anion type,etc.on the properties of printable MPSCs were investigated.Preferably,the octyltrimethylammonium chloride(OTAC)is introduced into perovskite precursor solution.The effects of OTAC on perovskite crystallization,device pore filling,charge extraction and the interaction between OTAC and Ti O2 were systematically studied.It is found that OTAC can upshift the Fermi level of Ti O2 and optimize the energy level alignment at Ti O2/perovskite interface.Additionally,OTAC can optimize the perovskite's crystallization and pore filling,thus inhibiting non-radiative recombination in devices.Benefiting from the dual effects of OTAC on suppressing non-radiative recombination and adjusting Fermi level adjustment,the VOC of MPSCs were significantly improved,which is about 120 m V higher than that of control devices and the highest VOC reached 1048 m V.The optimal MPSCs exhibit a PCE of 16.53%with a remarkable VOC of 1007 m V,a JSC of 23.56 m A/cm2,and an FF of 0.70,which was significantly higher than the devices without additives or with MACl additive.(3)Inorganic lead-free double perovskite materials were tried as light absorbers for printable MPSCs.A new type inorganic perovskite material Cs4Cu Sb2Cl12 was synthesized by hydrochloric acid solution method,aqueous solution method,hydrothermal method and ultrasonic stripping method.Meanwhile,inorganic perovskite materials with different band gaps were synthesized by adjusting the composition.The application of these inorganic perovskite materials through different methods in MPSCs were investigated.It's found that printable MPSCs based on these materials exhibit current-voltage characteristic due to capacitance effect rather than photovoltaic effect.The results show that this type of material has a significant capacitance effect in printable MPSCs. |
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