Interfacial Passivation Engineering of Perovskite Solar Cells with Fill Factor over 82% and Outstanding Operational Stability on n-i-p Architecture

Abstract

Tremendous efforts have been dedicated toward minimizing the open-circuit voltage deficits on perovskite solar cells (PSCs), and the fill factors are still relatively low. This hinders their further application in large scalable modules. Herein, we employ a newly designed ammonium salt, cyclohexylethylammonium iodide (CEAI), for interfacial engineering between the perovskite and hole-transporting layer (HTL), which enhanced the fill factor to 82.6% and consequent PCE of 23.57% on the target device. This can be associated with a reduction of the trap-assisted recombination rate at the 3D perovskite surface, via formation of a 2D perovskite interlayer. Remarkably, the property of the 2D perovskite interlayer along with the cyclohexylethyl group introduced by CEAI treatment also determines a pronounced enhancement in the surface hydrophobicity, leading to an outstanding stability of over 96% remaining efficiency of the passivated devices under maximum power point tracking with one sun illumination under N 2 atmosphere at room temperature after 1500 h.

Employing 2D‐Perovskite as an Electron Blocking Layer in Highly Efficient (18.5%) Perovskite Solar Cells with Printable Low Temperature Carbon Electrode

“…From our measurements, we can assume that the 2D perovskite EBL can effectively suppress charge carrier recombination at the perovskite/back electrode interface of the device. [ 16,34,35 ]…”

“…Moreover, the energetic barrier induced by the higher conduction band of the 2D perovskite passivation layer compared to the 3D perovskite can effectively block electron back transfer. [ 15,16 ] Furthermore, the use of 2D perovskites having bulky ammonium cations can improve the stability of PSCs by protecting the underlying layers from external degradation factors such as moisture diffusion. [ 17,18 ]…”

“…Moreover, the energetic barrier induced by the higher conduction band of the 2D perovskite passivation layer compared to the 3D perovskite can effectively block electron back transfer. [15,16] Furthermore, the use of 2D perovskites having bulky ammonium cations can improve the stability of PSCs by protecting the underlying layers from external degradation factors such as moisture diffusion. [17,18] In this work, we employed a 2D perovskite as an electron blocking layer (EBL) with its implementation of surface passivation on top of a 3D perovskite light absorber in printable low-temperature HTM-free C-PSCs.…”

Buried Interface Modification in Perovskite Solar Cells: A Materials Perspective

“…[31][32][33][34][35] A lack of in-depth understanding of the heterojunction interfaces and appropriate interface designs, specifically the buried interfaces under polycrystalline perovskite films, is impeding further advancements in perovskite photovoltaic performance and stability. [36][37][38][39][40][41][42] To date, many researches mainly focus on the top surfaces of perovskite. [43][44][45][46][47] However, due to the accumulation of deep-level trap states, it is known that unfavorable non-radiative recombination losses that impede device power outputs exist at the interfaces with bottom contact layers.…”

In Situ Graded Passivation via Porphyrin Derivative with Enhanced Photovoltage and Fill Factor in Perovskite Solar Cells

“…[5][6][7][8][9] However, the formation of defects on the surface and grain boundaries of the perovskite films is inevitable when conventional solution-processed processes are used. [10,11] These defects provide sites for nonradiative recombination and play a role in the perovskite degradation which compromises both device performance and stability. [12,13] Theoretical studies have indicated that the defects mainly consisted of I vacancy defects (VI) and I vacancies replaced by Pb antisite defects (PbI) because of their low formation energy.…”