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[Display omitted] • Iodine ligand-coupled PbS QDs film was firstly used to modify ZnO ETLs to boost photovoltaic performance of PSCs. • Introducing PbS-TBAI layer improves crystal quality of perovskite and forms cascade energy band structure. • A maximum PCE of 20.53 % has been achieved in the PSCs based on ZnO/PbS-TBAI-80 ETLs. Zinc oxide (ZnO) was traditional cathode material for solar cells due to excellent photoelectric properties. However, when ZnO is used as electron transport layers (ETLs) in perovskite solar cells (PSCs), the occurred deprotonation reactions can easily lead to the decomposition of perovskite layer. Herein, we reported a simple and controllable low-temperature strategy to overcome above problem for achieving high-efficient and stable ZnO based planar PSCs, i.e. the colloidal PbS QDs and tetrabutylammonium iodide (TBAI) was sequentially spin-coated on ZnO ETLs and then mild post-annealing process was carried out to obtaining ZnO/PbS-TBAI compact layer. Due to the iodine ligands from TBAI, the PbS-TBAI films act as both surface wetting control layer and electric dipole layer to adjust the crystal growth of perovskite films and charge behavior within devices. The better non-wetting surface of ZnO/PbS-TBAI ETLs improves the crystallization of the perovskite films by suppressing heterogeneous nucleation. And the unique energy level alignment of ZnO/PbS-TBAI induced by tunable surface dipole moment of TBAI boosted hetero-interface charge extraction of PSCs. Consequently, the optimized ZnO/PbS-TBAI based PSCs exhibits the power conversion efficiency (PCE) of 20.53 %, which is the champion PCE of ZnO PSCs with MAPbI 3 as the absorption layer. Stability tests also proved that the PCE of ZnO/PbS-TBAI based PSCs remains more than 86 % after exposure to 40 % humidity for 30 days, which is much more superior to that of control device. We firstly used iodination PbS QD films in this work to achieve higher photovoltaic performance in ZnO based PSCs, which prompts the further application of QDs materials within optoelectronic devices. [ABSTRACT FROM AUTHOR]

The fragile framework of the organic–inorganic metal halide perovskite has been strengthened for improving the stability of the PSCs by a multifunctional 2-amino-acetamidobenzotrifluoride (called BDP) with –NH 2 , C=O, and -CF 3 groups, simultaneously yielding a high efficiency of 21.62% for MAPbI 3 -based solar cells. [Display omitted] • A novel BDP-perovskite composite was developed for efficient and stable PSCs. • The BDP improved perovskite quality by retarding crystallization process. • The perovskite framework is reinforced by forming N-H...F bond with BDP. • The PCE of the BDP-treated device increased to 21.62% with a high V oc of 1.21 V. Perovskite solar cells (PSCs) are one of the most prospective photovoltaic devices because of their excellent photoelectric properties, yet their stability remains challenging. Apart from the reported passivation or encapsulation strategies, reinforcing the inherent framework of the perovskite is recognized as a substantial approach to stabilizing the PSCs. Herein, a multifunctional 2-amino-acetamidobenzotrifluoride (called BDP) with –NH 2 , C = O, and -CF 3 moieties is meticulously screened to strengthen the perovskite framework. The electron-donating groups of the BDP (–NH 2 and C = O) can simultaneously modify the crystallization process and achieve passivation, which devoted to reducing defect density; -CF 3 is used as a hydrophobic chemical stabilizer to form a moisture-resistant layer on the perovskite surface and suppress the MA+ ion migration by forming a hydrogen bond. Notably, the presence of the BDP also achieves a better energy level matching at the perovskite/hole transfer layer interface. Consequently, the power conversion efficiency (PCE) of MAPbI 3 solar cells is remarkably improved from 18.47% to 21.62%. Compared with the control devices, the PCE remains relatively stable under harsh external environmental conditions. Furthermore, the BDP also inhibits the lead leakage of PSCs, which is conducive to environmental applications. [ABSTRACT FROM AUTHOR]