Gold Nanoparticles Functionalized with Fullerene Derivative as an Effective Interface Layer for Improving the Efficiency and Stability of Planar Perovskite Solar Cells

Abstract

Titanium dioxide (TiO2) is an extensively used electron transporting layer (ETL) in n–i–p perovskite solar cells (PSCs). Although, TiO2 ETL experiences the high surface defect together with low electron extraction ability, which causes severe energy loss and poor stability in the PSC. In this study, a new intermediate layer consisting of gold nanoparticles functionalized with fully conjugated fullerene C60 derivative (C60‐BCT@Au NPs) that enhances the interfacial contact at ETL/perovskite interface leading to a perovskite film with improved crystallinity and morphology is reported. Moreover, the studies demonstrate that the interface modification of the TiO2 ETL with C60‐BCT@Au NPs substantially improves the charge extraction efficiency from the perovskite layer and suppresses charge recombination processes. Consequently, the resulting device yields a champion efficiency of 19.08% as well as devaluation in hysteresis. In addition, the unencapsulated PSCs with c‐TiO2/C60‐BCT@Au NPs ETL retain 83% and 90% of their original PCEs after 500 h storage in air and exposure to continuous UV illumination for 200 h, respectively. This study provides an effective method to address the electron transporting issues between perovskite and c‐TiO2 ETL for developing stable and efficient PSCs.

Targeted Molecular Design of Functionalized Fullerenes for High‐Performance and Stable Perovskite Solar Cells

“…By taking advantage of the strong interaction between sulfur and gold, Hong et al further studied gold nanoparticle's functionalized fullerene derivative (C 60 ‐BCT@Au NPs) as displayed in Figure 3g. [ 48 ] The introduced surface plasmon resonance property of Au NPs was found to affect optical and electron transfer characteristics of the ETL, and in turn, yielded a champion PCE of over 19% as well as devaluation in hysteresis. Furthermore, to explore the multifunction of fullerene IL, Yang et al reported a multifunctional fullerene derivative, PCBB‐2CN‐2C8 (Figure 3c), with cyano, carboxyl, and oxyalkyl groups simultaneously functionalizing the fullerene cage to realize TiO 2 interface engineering, which effectively enhanced charge extraction and passivated TiO 2 surface, resulting in 20.7% improvement in PCE.…”

Efficient Perovskite Solar Cells with Cesium Acetate-Modified TiO2 Electron Transport Layer

“…Chavan et al utilized tantalum pentoxide (Ta 2 O 5 ), niobium pentoxide (Nb 2 O 5 ), and titanium nitride (TiN) as a passivation layer to improve device performance in the mesoscopic heterojunction PSCs. The results reveal that surface passivation reduces the recombination and improves the charge transport at the perovskite/mp-TiO 2 contact surface. − It was also reported that a new intermediate layer consisting of gold nanoparticles functionalized with fully conjugated fullerene C 60 derivative (C 60 -BCT@Au NPs) was used to modify the c-TiO 2 and perovskite layers, facilitating the electron transfer at the ETL/perovskite interface and long-term stability …”

“…22−25 It was also reported that a new intermediate layer consisting of gold nanoparticles functionalized with fully conjugated fullerene C 60 derivative (C 60 -BCT@Au NPs) was used to modify the c-TiO 2 and perovskite layers, facilitating the electron transfer at the ETL/perovskite interface and longterm stability. 26 In some previous reports, Cs-based compounds were used as a surface modifier of ETLs to reduce the electron injection barrier and energy losses of interfaces for PSCs. Zhao et al utilized cesium acetate (CsAC) to modify the perovskite/HTL interface, demonstrating the benefits of stabilizing unblocked mobile ions of perovskite and an optimized PCE of 20.9%.…”

Simple Ball‐Milled Molybdenum Sulfide Nanosheets for Effective Interface Passivation with Self‐Repairing Function to Attain High‐Performance Perovskite Solar Cells

“…[ 2 ] However, the stability is still one of the main problems for the performance of PSCs, which is related to the interface layer. [ 3 ] Although conventional organic hole transport layers (HTLs) (such as, poly(3,4‐ethylenedioxythiophene): poly(styrenesulfonate), 2,2′,7,7′‐tetrakis(N,N‐dipmethoxyphenylamine)‐ 9,9′‐spirobifluorene (Spiro‐MeOTAD), and poly(triarylamine)) have a well‐aligned valence band (VB) with perovskite, the simple solution preparation and deposition and high current density throughput, their low crystallization temperature, the weak interaction tendency with the perovskite, [ 4,5 ] and the doping process with hygroscopicity and deliquescence can result in a significant reduction in long‐term stability of these devices. Besides doping processing, [ 6 ] the passivation of the perovskite/HTL interface has been carried out successfully by varieties of interfacial engineering methods, such as 2D perovskite layers, [ 7 ] ligand‐based modification, [ 4,8 ] or even inorganic materials.…”