【作者】 张凯；

【导师】 王浩；

【作者基本信息】 湖北大学 ， 微电子学与固体电子学， 2020， 硕士

【摘要】 钙钛矿太阳能电池（PSCs）因其低廉的成本和较高的光电转换效率（PCE）而成为最有前景的太阳能转换技术之一。以SnO₂作为电子传输层（ETL）的平面PSCs因为工艺简单且能耗较低而被广泛关注。但是,现有的大部分SnO₂制备工艺要求相对较高的退火温度（≥150^oC）,这阻碍了PSCs产业化和柔性化的发展,为此本论文介绍了一种低温化学浴法制备出质量较高的金红石相SnO₂ ETL,并研究SnO₂基PSCs的光电性能。首先通过对SnCl₄前驱液浓度和退火温度的控制,优化了SnO₂薄膜的表面形貌和光电性能。在0.3 M SnCl₄溶液和100 ^oC热处理条件下获得了均匀的、高结晶度和强透光率的SnO₂ ETL,这有利于SnO₂基MAPb I₃电池中提高电子的输运速度和减弱复合损耗。PSCs器件的最高PCE为16.78%,迟滞指数（HI）从0.76减小到0.31。使用二次浴修饰法进一步优化SnO₂薄膜,细化了ETLs的表面颗粒,钝化了缺陷,减少了ETLs与钙钛矿界面上的电荷复合,降低了PSCs的反向饱和电流和迟滞现象。0.035 M SnCl₄二次浴修饰后的2-SnO₂（0.035）基PSCs器件的最高PCE为17.71%,HI为0.11,并且未经封装的PSCs器件持续暴露在空气中60天后,仍能保持初始PCE的85%以上。然后介绍了混合钙钛矿（FAPb I₃）_X（MAPb Br₃）_1-X的制备工艺,基于1.6 M（FAPb I₃）_0.85（MAPb Br₃）_0.15的PSCs实现了19.22%PCE,HI为0.268。之后分别对其进行2.5%、5%和7.5%K⁺掺杂,结果显示5%K⁺掺杂时PSCs器件的PCE最高,HI最小。K⁺掺杂时卤族元素的引入会影响PSCs器件迟滞和光电性能,对比引入不同卤族元素时混合钙钛矿的微观形貌、带隙和器件光电性能,得出掺杂KI最优。5%K⁺掺杂的KFAMA基PSCs器件的最佳PCE为17.63%,HI减小到0.011。此时,K⁺以部分游离部分替代的掺杂方式进入（FAPb I₃）_0.85（MAPb Br₃）_0.15中,改善了钙钛矿晶粒尺寸,抑制了弗伦克尔缺陷的形成,解决了PSCs的迟滞现象。最后对比Cs⁺掺杂,进一步证实K⁺掺杂能有效抑制PSCs器件迟滞现象。最后使用100mL异丙醇（IPA）修饰5%KI-FAMA钙钛矿界面,制备结构为FTO/SnO₂/KI-FAMA/Spiro-OMe TAD/Ag的PSCs器件。IPA修饰后,表面有机残留物被清除,钙钛矿晶粒尺寸变大,钙钛矿表面的缺陷密度减小,组装成PSCs器件后,PCE从11.01%提升到14.57%。更多还原

【Abstract】 Perovskite solar cells（PSCs）have become one of the most promising solar energy conversion technologies for low cost and high photoelectric conversion efficiency（PCE）.Planar PSCs with SnO₂ electronic transport layer（ETL）are widely concerned because of its simple process and low energy consumption.However,most technologies for SnO₂ ETL require relatively high annealing temperature（≥150 ^oC）,which hinders the industrialization and flexibility of PSCs.In this thesis,rutile SnO₂ ETL with high quality has been prepared via low-temperature chemical bath,and the photoelectric properties of SnO₂-based PSCs have been studied.Through the control of precursor SnCl₄ concentration and annealing temperature,the surface microstructures and optoelectronic performances of SnO₂ films are optimized.Uniform SnO₂ ETLs with high crystallinity and transmittance are obtained from 0.3 M SnCl₄ solution and 100 ^oC heat-treatment,which is positive to improve the electron transport speed and weaken recombination loss in SnO₂based photovoltaic devices.The maximum PCE of PSCs is 16.78%,and the hysteresis index（HI）is reduced from0.76 to 0.31.Secondary-bath modification with 0.035 M SnCl₄ is proposed to decorate SnO₂ ETLs（2-SnO₂（0.035））.The PCE of PSCs based on 2-SnO₂（0.035）film are enhanced to 17.71%.Simultaneously,HI of PSCs is reduced to 0.11,since secondary-bath refines the surface particles of ETLs,passivates the defects and reduces charge recombination on the interfaces between the ETLs and perovskite.What’s more,the 2-SnO₂ based PSCs can remain 85.7%of the premier PCE after repositing in air for 60days.Then mixed perovskite（FAPb I₃）_X（MAPb Br₃）_1-X has been introduced.The PSCs based on 1.6 M（FAPb I₃）_0.85（MAPb Br₃）_0.15 achieve 19.22%PCE and 0.268 HI.In order to solve the hysteresis problem,2.5%、5%and 7.5%K⁺are doped into the mixed perovskite,respectively.The results show that the PCE of PSCs is the highest and the HI is the lowest when the doping ratio of K⁺is 5%.Then it is found that the introduction of halogens will affect the hysteresis and photoelectric properties of PSCs devices when K⁺is doped.By comparing the micro morphology,band gap and photoelectric properties of the devices when different halogens are introduced,it is found that KI doping is the best.The optimum PCE of 5%K⁺doped KFAMA based PSCs is 17.63%,and HI is reduced to 0.011.5%K⁺enters into（FAPb I₃）_0.85（MAPb Br₃）_0.15 in the form of partially free and partially substituted doping,which improves the grain size of perovskite,inhibits the formation of Frenkel defects and solves the hysteresis phenomenon of PSCs.Finally,compared with Cs⁺doping,K⁺doping can effectively inhibit the hysteresis of PSCs.At last,the 5%KI-FAMA perovskite interface is modified via 100mL isopropanol（IPA）.The structure of PSCs is FTO/SnO₂/KI-FAMA/Spiro-OMe TAD/Ag.After IPA modification,the organic residues on the surface are removed,the size of perovskite grain increases,and the defect densities on the perovskite surface decrease.更多还原