Molecular engineering of interface modifier for efficient and stable perovskite solar cells

Abstract

Power conversion efficiencies (PCE) of perovskite solar cells (PSCs) has rising from the initial 3.8% to the state-of-the-art 25.7% within the past few years. Most highly efficient PSCs utilize an n-type layer of mesoporous titanium dioxide or tin oxide in an n-i-p device configuration, in which organic conductors are widely used to transport holes into an adjoined metal. Thus far, a variety of efforts have been devoted to achieve a defect-less perovskite film with high-quality morphologies for realizing reduced loss-in-potential outcomes and enhanced efficiency levels. To ensure both efficiency and stability of perovskite solar cells, we suggested a rational interface design at the interface of the perovskite and the HTM that would lead to the effective passivation of surface defects, a favorable energy-level alignment for facilitating hole extraction, and robust interfacial contact against an environmental stimulus. Through full optimization by adopting function-tailored interface modifier (IM), the champion cell exhibited a PCE of 23.6% under forward scan and a stabilized PCE of 23.1% under MPPT. Stabilized interface with IM and PTAA led to excellent thermal and operational stability for more than 1000 hrs. We expect that our strategy of rational interface design in efficient and stable PSCs will greatly contribute to commercialization in the future.