基于SnO_(2):DPEPO混合电子传输层的钙钛矿太阳能电池性能研究

Performance of perovskite solar cells based on SnO_2:DPEPO hybrid electron transport layer

电子传输层是钙钛矿太阳能电池的重要功能层,其表面及内部缺陷是限制钙钛矿太阳能电池性能提升的重要一环.双电子传输层(双ETL)策略虽然可以改善电子在功能层之间提取与传输,但是双ETL内部存在的独立界面以及不同ETL材料晶胞不匹配问题导致了额外的非辐射复合.基于此,本文提出了将二[2-((氧代)二苯基膦基)苯基]醚(DPEPO)引入到SnO_(2)中设计混合电子传输层的策略,该策略在钝化SnO_(2)中本征缺陷的同时,可以避免由于额外界面的存在而导致的缺陷态,有效改善了电子的提取与传输.并且进一步实现了对钙钛矿薄膜的结晶调控,提升钙钛矿太阳能电池性能,最终收获了基于宽带隙钙钛矿太阳能电池21.53%的功率转换率,其中开路电压(V_(OC))达到了1.220 V,短路电流(J_(SC))为23.19 mA/cm^(2),填充因子(FF)高达76.11%.研究表明混合电子传输层策略可以有效优化载流子传输动力学,促进钙钛矿高质量结晶,对制备高性能太阳能电池具有一定指导意义.

The electron transport layer is an important functional layer of perovskite solar cells,and its surface and internal defects are critical parts of limiting the performance improvement of perovskite solar cells.The double electron transport layer(double ETL)strategy can effectively passivate inherent defects in the electron transport layer(such as SnO_(2))and improve electron extraction and transport between the functional layers,providing an effective way for developing efficient and stable PSCs.However,due to the existence of independent interfaces in the dual ETL,the cell mismatch in different ETL materials also leads to additional carrier defects,hindering the continuous advancement of the dual ETL strategy.This work proposes a strategy for introducing di[2-((oxo)diphenylphosphino)phenyl]ether(DPEPO)into SnO_(2)ETL to design a hybrid electron transport layer strategy.Using the hole-blocking effect of DPEPO,which has a higher HOMO energy level and good ability to transfer electrons,the intrinsic defects in SnO_(2)are successfully passivated,while significantly improving the crystalline quality of the SnO_(2)film surface.So,avoiding the direct contact between the perovskite photoactive layer and the conductive substrate can effectively improve the extraction and transport of electrons.Due to the preparation of high-quality electron transport layer,the crystallization regulation of perovskite thin film is further achieved,thereby improving the performance of perovskite solar cells.Finally,21.53%of the power conversion rate is obtained,the open-circuit voltage(V_(OC))reaches 1.220 V,the shortcircuit current(J_(SC))is 23.19 mA/cm^(2),and the fill factor(FF)is 76.11%.This efficiency is 1.39%higher than that of the control one.It is shown that the hybrid electron transport layer strategy can not only optimize the carrier transport dynamics efficiently and reduce the device performance affected by the defects in the functional layer significantly,but also regulate the perovskite crystallization,which has the prospect for preparing high-performance solar cells.