유기전해질을 Dual-side Passivation 층으로 도입한 고효율 고안정성 페로브스카이트 태양전지

Abstract

Interface engineering at the interface between the perovskite layer and the charge transport layer (CTL), or CTL and metal electrodes, is critical for demonstrating the efficient and stable perovskite solar cells (PSCs). Herein, we demonstrate the efficient and stable PSCs by introducing the organic electrolytes (OEs) as a “dual-side passivation layer” in both p-i-n and n-i-p configuration of PSCs. Firstly, a newly synthesized bathocuproine (BCP)-based nonconjugated polyelectrolyte (poly-BCP) is introduced between the tin oxide (SnO2) CTL and the perovskite layer in the n-i-p configuration. Poly-BCP effectively passivate oxygen-vacancy defects of the SnO2 side and simultaneously scavenges ionic defects of perovskite side, suppressing both bulk and interfacial nonradiative recombination in PSCs. As a result, the modified PSCs exhibited a high power conversion efficiency (PCE) of 24.4% and a high open-circuit voltage of 1.21 V. Furthermore, the non-encapsulated PSCs show excellent long-term stability by retaining 93% of the initial PCE after 700 h under continuous 1-sun irradiation in nitrogen atmosphere conditions. Secondly, amine-functionalized small molecule electrolytes (SMEs) are introduced as passivation layer between the PCBM CTL and metal electrode (here, Cu) in the p-i-n configuration. A strong coordination bond of Cu─N forms at the Cu/SMEs interface, leading to the layer–layer growth mode for the dense formation of Cu electrodes with a strong adhesion to the CTL. Thus, this modified electrode prevents the ingress of moisture into the PSCs, resulting in outstanding moisture stability; the efficiency of non-encapsulated PSCs retains 90% of the initial PCE after 200 days of exposure to atmospheric air (25 ℃, relative humidity [RH] ~20–40%). Under harsher conditions (e.g., 25 ℃/RH65%, 25 ℃/RH85% and immersion in water) for a considerable time period, the modified PSCs manifest relatively no degradation compared with the pristine PSCs.