Efficient Defect Passivation for Perovskite Solar Cells by Controlling the Electron Density Distribution of Donor‐π‐Acceptor Molecules

Abstract

Organic–inorganic hybrid perovskite solar cells (PSCs) are a promising photovoltaic technology that has rapidly developed in recent years. Nevertheless, a large number of ionic defects within perovskite absorber can serve as non‐radiative recombination center to limit the performance of PSCs. Here, organic donor‐π‐acceptor (D‐π‐A) molecules with different electron density distributions are employed to efficiently passivate the defects in the perovskite films. The X‐ray photoelectron spectroscopy (XPS) analysis shows that the strong electron donating N,N‐dibutylaminophenyl unit in a molecule causes an increase in the electron density of the passivation site that is a carboxylate group, resulting in better binding with the defects of under‐coordinated Pb2+ cations. Carrier lifetime in the perovskite films measured by the time‐resolved photoluminescence spectrum is also prolonged by an increase in donation ability of the D‐π‐A molecules. As a consequence, these benefits contribute to an increase of 80 mV in the open circuit voltage of the devices, enabling a maximum power conversion efficiency (PCE) of 20.43%, in comparison with PCE of 18.52% for the control device. The authors' findings provide a novel strategy for efficient defect passivation in the perovskite solar cells based on controlling the electronic configuration of passivation molecules.

Alkyl‐Chain‐Regulated Charge Transfer in Fluorescent Inorganic CsPbBr3 Perovskite Solar Cells

“…C12‐QDs tailored device achieves a higher V bi of 1.32 V, which is an indicator of reduced screening effect caused by charge carrier recombination. This is mainly attributed to the larger driving force (the energy levels of QDs are provided in Supplementary Figure S4) and reduced interface trap states . Furthermore, the larger slope of device tailored with C12‐QDs than that of other PSCs means a lower interfacial charge density, suggesting an improved charge extraction behavior.…”

3 D NiO Nanowall Hole‐Transporting Layer for the Passivation of Interfacial Contact in Inverted Perovskite Solar Cells

“…in which V TFL , e 0 , e, e and L represent the trap-filling limit voltage, vacuum permittivity,r elative dielectric constanta nd thickness of the perovskite film, respectively. [37,38] This directly indicated that the optimal mesoporous structure of film (6 h) was more favorable for effectively passivating the trap states density in the NiO/perovskite interface. Furthermore, the interfacial properties between NiON Ws HSC and perovskite film were furtherc haracterized by capacitance-voltage (C-V)m easurements.T he deduced Mott-Schottky curve ( Figure 3b)p rovides the built-in-potential (V bi )v alue of these devices (FTO/NiO/Perovskite/Ag).…”

Inverted Perovskite Solar Cells Based on Small Molecular Hole Transport Material C8‐Dioctylbenzothienobenzothiophene

“…The result indicates that the HOMO level of C 8 ‐BTBT (150 °C) is deeper than that of PEDOT:PSS, better matched with the valence band of CH 3 NH 3 PbI 3 perovskite (–5.4 eV). As a result, more efficient hole extraction from the perovskite layer and a lower energy loss can be expected, which leads to a higher V oc . Moreover, the higher lowest unoccupied molecular orbital (LUMO) level of C 8 ‐BTBT (–2.2 eV) will effectively block electrons, thereby reduce charge carrier recombination.…”

“…Organic‐inorganic hybrid perovskites have attracted tremendous attention due to their capabilities in appropriate band gap, high extinction coefficient, and long‐range photocarrier diffusion length, which opened up exceptionally rapid progress in power conversion efficiency (PCE) of the perovskite solar cells (PVSCs) in recent years …”