绿色双溶剂法制备高效稳定钙钛矿太阳能电池

High-performance and stable perovskite solar cells prepared with a green bi-solvent method

采用毒性小、环境友好的乙二醇甲醚(ethylene glycol monomethyl ether,EGME)与水混合的双溶剂(体积比为1:1)溶解CsBr,通过提高CsBr的溶解度,减少了后续Cs Br的甲醇溶液的旋涂遍数,简化了电池制备流程。通过优化Cs Br的甲醇溶液的旋涂遍数发现,在旋涂1遍200 mg·mL^(-1)CsBr的水/EGME溶液的基础上旋涂2遍15 mg·mL^(-1)Cs Br的甲醇溶液,所制备的Cs Pb Br_(3)钙钛矿太阳能电池(perovskite solar cells,PSCs)拥有最佳的性能,实现了1.44 V的开路电压(open-circuit voltage,VOC),6.26 mA·cm^(-2)的短路电流密度(short circuit current density,JSC),74.57%的填充因子(fill factor,FF)及最高6.72%的光电转换效率(photoelectric conversion efficiency,PCE)。

To simplify the fabrication procedures and improve the film quality,herein we used a bi-solvent system containing water and ethylene glycol methyl ether(EGME),which is less toxic and environmentally friendly.The bi-solvent(Volume ratio:1:1)can dissolve CsBr and improve the solubility of CsBr,decreasing rapidly the spinning times of CsBr methanol solution and streamlining immensely multistep processes into a classical two-step methodology.The results from scanning electron microscopy(SEM)images and X-ray diffraction(XRD)patterns verify the formation of a compact,homogeneous,and uniform CsPbBr_(3)film by the bi-solvent system.Based on this bi-solvent system,the ideal parameters during the film deposition were also discovered.In addition,we notice that the CsPbBr_(3)film still existed in some large-size random phases,which can be deducted as the excessive CsPb2Br5 phase through XRD patterns.For further perfection,we explore the influence of CsBr methanol solution spinning times right after the modified two-step process.The subsequently-spinning CsBr can act as a surface modifier to diminish the undesired impurity,thus enhancing the film quality and the efficiency of as-constructed CsPbBr_(3)-based perovskite solar cells(PSCs).As a result,CsPbBr_(3)-based PSCs,prepared by spinning coating one time with a water/EGME solution and two times with the methanol solution of CsBr,had the optimal performance.It can reach open-circuit voltage(VOC),short circuit current density(JSC),fill factor(FF)of 1.44 V,6.26 mA·cm^(-2),74.57%,and the ultimate photoelectric conversion efficiency(PCE)attained 6.72%.