Interface Passivation of Inverted Perovskite Solar Cells by Dye Molecules

Abstract

The interface between [6,6]-phenyl C61-butyric acid methyl ester (PC61BM) and the electrode has a critical effect on the performance of inverted perovskite solar cells (PSCs). Three organic cationic cyanine dye molecules with different highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) states are designed to passivate the PC61BM and Ag electrode interface to improve PSCs performance. The effects of energy-level alignment and the interfacial charge transfer resistance on the device performance are compared and studied. The dye interface passivation layer significantly reduces charge recombination. Moreover, the ClO4 – anions associated with the dye molecules improve the charge extraction and charge transport in the devices. Reduced interface charge recombination and improved charge transport are confirmed by photoluminescence (PL), time-resolved photoluminescence (TRPL), electrochemical impedance spectra (EIS), and charge-only device performance studies. The PSCs with one of the dyes as an interface passivation layer show an optimized power conversion efficiency (PCE) of 19.14% with an open-circuit voltage (V oc) of 1.09 V, a short-circuit current density (J sc) of 22.87 mA/cm2, and a fill factor (FF) of 76.81%. The devices maintain over 90% of the initial PCE for 120 h of storage under an ambient environment (25 °C and 30 ± 5% relative humidity (RH). The use of small dye molecules as an interface passivation layer to reduce charge recombination in PSCs represents a paradigm for improving the performance and stability of PSCs.

Universal Surface Passivation of Organic–Inorganic Halide Perovskite Films by Tetraoctylammonium Chloride for High-Performance and Stable Perovskite Solar Cells

“…A stoichiometric amount of CsI from a solution of 1.5 mM CsI in DMSO was added to obtain the final composition. The mixed perovskite is deposited at 4000 rpm for 40 s, and chlorobenzene was dropped as the antisolvent in the middle of the spinning procedure and subsequently annealed at 100 °C for 1 h. MAPbI 3 is prepared following the literature. , After that, various concentrations of TOAC in 2-propanol were spin-coated on perovskite layers at 4000 rpm for 30 s and annealed at a mild temperature of 70 °C for 10 min. The optimized TOAC concentration for the mixed perovskite is 2.5 mM, and for MAPbI 3 , it is 0.5 mM in 2-propanol.…”

“…The characterization of perovskite and modified perovskite films was performed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), ultraviolet–visible (UV–vis), PL, and TRPL, and all I – V , external quantum efficiency (EQE), and electrical impedance spectroscopy (EIS) device measurements were done using the apparatus described in reference. , …”

Efficient and stable perovskite solar cells using manganese-doped nickel oxide as the hole transport layer

“…Dai and his coworkers also claimed that the ion migration by the external bias inside the perovskite films during a relatively long measurement period can result in the decreased integrate current density for the EQE measurement. 61 Therefore, the obtained integrated current density that is smaller than J SC within 10–20% is acceptable. 60 In this work, the difference between the integrated current density and J SC is found to be 9.4% and 17.3% for devices based on the 0.5 mol% Mn-doped and un-doped NiO x HTLs, respectively, which is believable.…”

“…36 Bao et al fabricated PSCs based on Rb-doped NiO x HTL, which aged in the dark at room temperature with 30% relative humidity. 61,62 The device retained <70% of initial efficiency after 700 h (29 days) storage. Compare to other doped elements such as K, La, Li, or Li–Co–Mg co-dopant, a smaller amount of the Mn dopant is needed to achieve comparable device performance, and Mn ions would not damage the perovskite layer as released from NiO x lattice.…”

Fabrication of efficient and stable perovskite solar cells in open air through adopting a dye interlayer

“…5a, the PL peak intensity of the perovskite/HQTh-EC lm was noticeably reduced compared with that of the control lm, implying more effective carrier transport. 30,31 The PL peak presented a blue-shi from 766 nm to 764 nm, suggesting lower electron trap-state density for the perovskite. 32 Fig.…”