Novel dual-modification strategy using Ce-containing compounds toward high-performance flexible perovskite solar cells

Abstract

The carrier non-radiative recombination loss caused by numerous interfacial defects existing between perovskite and neighboring charge transport layers, such as SnO2/perovskite and perovskite/spiro-OMeTAD, which greatly restricts the performance improvement of flexible perovskite solar cells (PSCs). Herein, we devised a novel dual-modification strategy using Ce-containing compounds (Ce2(SO4)3 and Ce(SO4)2) to minimize interfacial defect density at the interface of SnO2/perovskite and perovskite/spiro-OMeTAD respectively, thus enhancing the performance and stability of flexible PSCs. It was revealed that the introduction of Ce2(SO4)3 interface layer was conducive to ameliorating the electrical properties of SnO2 and significantly reducing the SnO2/perovskite interface defects. Moreover, the Ce(SO4)2 was adopted as a novel oxidant to achieve the rapid oxidation of spiro-OMeTAD, thus enhancing the hole mobility of bulk spiro-OMeTAD and suppressing perovskite/spiro-OMeTAD interface defects. Therefore, reduced non-radiative recombination losses near the two interfaces of the perovskite layer could be achieved by such a novel and comprehensive modification strategy. In consequence, the Ce-modified flexible and rigid PSCs achieved excellent photoelectric conversion efficiency (PCE) of 19.34 % and 22.62 %, respectively. Notably, the optimized flexible PSCs exhibited outstanding mechanical durability, and 83.2 % of the initial PCE was maintained after 3000 bending cycles.