Critical Role of Functional Groups in Defect Passivation and Energy Band Modulation in Efficient and Stable Inverted Perovskite Solar Cells Exceeding 21% Efficiency

Abstract

Interfaces in perovskite solar cells (PSCs) are closely related to their power conversion efficiency (PCE) and stability. It is highly desirable to minimize the interfacial nonradiative recombination losses through rational interfacial engineering. Herein we develop an effective and easily reproducible interface engineering strategy where three mercaptobenzimidazole (MBI)-based molecules are employed to modify the perovskite/electron transport layer (ETL) interface. MBI and MBI-OCH3 can not only passivate defects at surface and grain boundaries (GBs) of perovskite films but can also improve energy level alignment (ELA), which leads to enhanced PCE and stability. Consequently, the PCE is improved from 19.5% for the control device to 21.2% for MBI-modified device, which is among the best reported inverted MAPbI3-based PSCs. In contrast, incorporation of MBI-NO2 increases defect density and negligibly influences the energy level alignment. This work indicates that defect passivation and ELA modulation can be achieved simultaneously through modulating functional groups in interface modification molecules.

Mixed-Phase Low-Dimensional Perovskite-Assisted Interfacial Lead Directional Management for Stable Perovskite Solar Cells with Efficiency over 24%

“…As shown in Figures c and S8, there were two strong peaks located around 143.1 and 138.3 eV, corresponding to the Pb 4f 5/2 and Pb 4f 7/2 , respectively. In contrast with the control perovskite, the Pb 4f peaks of the unannealed MT-Im (143.2 and 138.4 eV) and MT-Im perovskite (143.4 and 138.6 eV) exhibited evident position shift to higher binding energy because of the strong chemical interaction between the introduced MT-Im and Pb 2+ in perovskite films. , Moreover, the MT-Im perovskite film displayed a more noticeable shift to higher energy, confirming the stronger interaction between the MT-Im and Pb 2+ due to the strong passivation effect of the MT-Im after annealing. For the control and unannealed MT-Im perovskite films, two additional weak peaks emerge at about 141.5 and 136.6 eV, indicating the existence of Pb 0 , which will become the nonradiative centers and finally will result in the poor photovoltaic performance.…”

“…In contrast with MT-Im (Figure 2e), the characteristic peaks of C=N and −S−C functional groups in PbI 2 + MT-Im moved from 1558.63 and 1288.04 cm −1 to 1553.31 and 1280.60 cm −1 , respectively. 34,36 In Figure S11, the 1 H characteristic peaks of −C−NH 2 and −S−CH 3 moved from 2.59 and 9.91 ppm (for the MT-Im sample) to 2.55 and 9.85 ppm (for the PbI 2 + MT-Im sample), respectively. 37,38 These results all further proved the interaction between the MT-Im and PbI 2 .…”

Double‐Side Crystallization Tuning to Achieve over 1 µm Thick and Well‐Aligned Block‐Like Narrow‐Bandgap Perovskites for High‐Efficiency Near‐Infrared Photodetectors

“…Many materials have been produced by various solution chemical methods, such as inorganic, [ 10–13 ] organic, [ 14,15 ] and hybrid materials. [ 16,17 ] Among emerging materials, hybrid organic–‐inorganic halide perovskites (ABX 3 : A = methylammonium [MA], formamidinium [FA], rubidium, and cesium [Cs]; B = Pb, Sn; X = Cl, Br, I) present great potentials as photoactive materials of PDs. [ 18–21 ] They not only can be easily prepared by the simple low‐temperature solution‐based method, but also harbor remarkable optoelectronic properties, especially the outstanding absorption coefficient with over an order of magnitude higher than that of silicon.…”

Enhanced Efficiency and Stability of NiOx-Based Perovskite Solar Cells Using [6,6]-Phenyl-C61-butyric Acid Methyl-Doped Poly(9-vinylcarbazole)-Modified Layer

“…3 Zheng et al used three mercaptobenzimidazole (MBI)-based molecules to modify the perovskite/ ETL interface. 4 The PCE is improved from 19.5% for the control device to 21.2% for the MBI-modified device. Liu et al inserted a layer of SnO 2 nanocrystals between the C 60 (as ETL) and the Ag electrode to promote the extraction and transmission of electrons.…”

“…Yan et al used PDI-PhCN as the electron transport layer (ETL) instead of [6,6]-phenyl-C 61 -butyric acid methyl (PCBM) to further improve the electron mobility . Zheng et al used three mercaptobenzimidazole (MBI)-based molecules to modify the perovskite/ETL interface . The PCE is improved from 19.5% for the control device to 21.2% for the MBI-modified device.…”