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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]

A supramolecular bridging strategy with 2, 5-diaminobenzotrifluorid (DTF) molecular binder as the repeating unit was introduced to form a supramolecular-perovskite composite. The supramolecular binder plays a role of bridging the perovskite crystal grains, passivating the traps states of the perovskite films and producing excellent environmental stability. [Display omitted] • A supramolecular bridging strategy with DTF as repeat unit was proposed. • Bridging effect induced by the S-DTF for perovskite films was revealed. • Moisture-resistant MAPbI 3 solar cells with excellent performance was achieved. • Photovoltaic performance of MAPbI 3 solar cells have been effectively improved. The manipulation of grain boundaries in polycrystalline perovskites is an indispensable consideration for the photovoltaic performance and environmental stability of solar cells, because perovskite films obtained by solution process will inevitably introduce many defects in the grain boundaries. Although additives based on small molecules have proven to be effective defect passivators, their high volatility and diffusibility cannot satisfy the stability requirements of perovskite films. As an upgraded approach, herein, we introduced a supramolecular bridging strategy with 2,5-diaminobenzotrifluorid (DTF) molecular binder as the repeating unit to form a supramolecular-perovskite composite. The supramolecular binder plays a role of bridging the perovskite crystal grains, passivating the traps states of the perovskite films and producing excellent environmental stability, which is superior to the conventional additive engineering. As a result, the power conversion efficiency of the MAPbI 3 solar cell has been significantly increased from 18.8% to 21.0 %. The perovskite solar cells with S-DTF maintaining 93% of their original efficiency for over 30 days (∼70% humidity) in air ambient without encapsulation, exhibiting an excellent long-term stability. This will inspire a wider range of ideas beyond the regular additive engineering for improving the performance of polycrystalline perovskite-based photoelectronic devices. [ABSTRACT FROM AUTHOR]