SnO_(2)双层电子传输层对钙钛矿太阳能电池界面电荷传输的影响

Effect of Bilayer SnO_(2) Electron Transport Layer on the Interfacial Charge Transport in Perovskite Solar Cells

为了改善基于SnO_(2)电子传输层的钙钛矿太阳能电池的界面电荷传输特性和迟滞现象,我们采用低温溶液处理工艺制备了4种不同类型的SnO_(2)电子传输层用于钙钛矿太阳能电池,包括由SnCl_(4)·5H_(2)O溶胶-凝胶层(Cl_(4)‑SnO_(2))、SnCl_(2)·2H_(2)O溶胶-凝胶层(Cl_(2)‑SnO_(2))和SnO_(2)纳米颗粒层(NP‑SnO_(2))与SnO_(2)胶体层(Col‑SnO_(2))两两相互作用形成的同质结SnO_(2)双层电子传输层和Col‑SnO_(2)单层电子传输层;并系统研究了不同SnO_(2)双层电子传输层对器件光电性能和迟滞现象的影响。通过扫描电镜(SEM)、X射线衍射(XRD)、稳态光致发光(PL)、电化学阻抗(EIS)和稳定性测试等表征证实,在Col‑SnO_(2)层下方插入Cl_(2)‑SnO_(2)层可更好地形成紧密接触,两者相互作用形成平滑紧凑的SnO_(2)双层纳米晶体结构与钙钛矿层之间具有良好的界面接触和更少的界面缺陷,表现出更优异的电子提取和传输特性。与基于Col‑SnO_(2)单层结构的器件(14.16%)相比,基于Cl_(2)‑SnO_(2)/Col‑SnO_(2)双层电子传输层结构的器件获得了15.01%的光电转换效率,正向扫描的光电转换效率提高了约23.3%,短路电流密度(Jsc)和填充因子(FF)均得到了改善,迟滞现象被明显抑制且表现出更好的稳定性。相比之下,基于Cl_(4)‑SnO_(2)/Col‑SnO_(2)双层结构器件的性能改善稍显逊色,基于NP‑SnO_(2)/Col‑SnO_(2)双层结构器件的性能反而有所下降。

SnO_(2)has the advantages of the wide bandgap,high optical transparency,high electron mobility,excellent UV stability,and lower preparation temperature.It is widely used in high-efficiency and stable perovskite solar cells(PSCs).However,the surface defects of SnO_(2)can cause serious hysteresis and other adverse effects.In order to improve the interfacial charge transport characteristics and hysteresis of perovskite solar cells based on the SnO_(2)electron transport layer.Four different types of SnO_(2)electron transport layers were prepared as electron transport layers(ETLs)for PSCs using low-temperature solution processing technology.SnCl_(4)·5H_(2)O(Cl_(4)-SnO_(2)),SnCl_(2)·2H_(2)O(Cl_(2)-SnO_(2)),and SnO_(2)nanoparticle(NP-SnO_(2))were used to form the bilayer ETL structure with SnO_(2)colloidal(Col-SnO_(2)).The effects of different SnO_(2)bilayer ETLs on the photoelectric performance and hysteresis of the device were systematically studied.Through analysis of scanning electron microscopy(SEM),X-ray diffraction(XRD),steady-state photoluminescence spectrum(PL),electrochemical impedance(EIS),and stability test,it can be confirmed that the surface of Cl_(4)-SnO_(2)/Col-SnO_(2)and Cl_(2)-SnO_(2)/Col-SnO_(2)films was smooth and compact with good coverage;and inserting a Cl_(2)-SnO_(2)layer under the Col-SnO_(2)layer can form better interface contact and fewer interfacial defects,which is beneficial to reduce the interfacial resistance and charge recombination,and exhibits more excellent electron extraction and transport characteristics.However,the nanostructure composed of the NP-SnO_(2)layer and the Col-SnO_(2)layer is not conducive to the growth of perovskite crystals,and the incompatible interface between the two causes serious charge recombination,which will affect the charge transfer.Compared with the device based on the Col-SnO_(2)single ETL device(14.16%),the device based on the Cl_(2)-SnO_(2)/Col-SnO_(2)bilayer structure obtained a photoelectric conversion efficiency of 15.01%,and the photoelectric conversion efficiency of the forward scan was increased by about 23.3%,short circuit current density(Jsc)and fill factor(FF)were improved,the hysteresis was obviously suppressed and showed better stability.