Kai-Chi Hsiao1,Ting-Han Lin1,Wei-Fang Su2,3,Ming-Chung Wu1
Chang Gung University1,Ming Chi University of Technology2,National Taiwan University3
Kai-Chi Hsiao1,Ting-Han Lin1,Wei-Fang Su2,3,Ming-Chung Wu1
Chang Gung University1,Ming Chi University of Technology2,National Taiwan University3
A carrier transport layer and its interfacial effects on an organometal halide perovskite light harvesting layer play an influential factor in either photovoltaic performance or long-term stability of a perovskite solar cell (OHPSC). Although the understandings of the carrier transport layers and interfacial effects on regular structured OHPSCs have been explored, knowledge of an interface between hole transport layer of NiO<sub>x</sub> and perovskite in an inverted OHPSC is still necessary to be developed. Here, we performed a universal NiO<sub>x</sub> film with the sequential passivation strategy of NiCl<sub>2</sub> (SPS-NiCl<sub>2</sub> treatment) for either wide bandgap or narrow bandgap of OHPSCs. The SPS-NiCl<sub>2</sub> treated NiO<sub>x</sub> film not only implements the passivation at the perovskite layer/NiO<sub>x</sub> film interface but also confers itself a gradient energy level of valance band inducing by chloride. Comprehensive characterizations reveal that the SPS-NiCl<sub>2</sub> treated NiO<sub>x</sub> film suppresses non-radiative recombination at the interface and enlarges the splitting of the quasi-Fermi level at the interfaces. The photoconversion efficiency (PCE) of the champion device comprised of the SPS-NiCl<sub>2</sub> treated NiO<sub>x</sub> film can achieve 19.53% with a record <i>Voc </i>of 1.16 V, the lowest <i>Voc </i>deficit of 390 mV in NiO<sub>x</sub> based inverted OHPSCs. The corresponding devices with encapsulation also exhibit superior long-term stability, and over 80% of initial PCE can be maintained after 1500 h damp-heat test. This study sheds the light on managing the interfacial issues of an inverted OHPSC and offers a feasible path to develop a universal hole transport layer for perovskite layers with different energy bandgap.