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In this paper, we have fabricated ternary PSC with BTP-eC9 as the host acceptor, IT-M as the guest acceptor, and PM6 as donor. The optimized ternary PSC (PM6:BTP-eC9:IT-M ratio is 1:1.2:0.2) has the highest power conversion efficiency (PCE) of 17.06 % compared to the PM6:BTP-eC9 binary PSC (16.46 %) and PM6:L8-BO reference binary PSC (16.92 %). We systematically investigated the effect of blend acceptors on morphology, photovoltaic performance and charge carrier dynamics. After the addition of IT-M to PM6:BTP-eC9 binary film, the highest J SC (from 26.39 to 26.82 mA cm−2) was achieved for optimized ternary PSCs compared to PM6:BTP-eC9 binary PSC, which was attributed to the high efficiency of light absorption in the medium to long-wavelength region of IT-M. Shallower lowest unoccupied molecular orbitals (LUMO) level of IT-M enlarged the optical bandgap, which leads to an increase in the open-circuit voltage (V OC , from 0.86 V to 0.875 V). In addition, a small amount of IT-M improves the surface and bulk morphology and crystallinity of the ternary film. The ternary films shown high charge mobility ability. This work demonstrates that supplementing the light absorption and broadening the optical bandgap of PM6:BTP-eC9 binary films by IT-M as third component can effectively improve the PCE and obtain higher photovoltaic performance than that of PM6:BTP-eC9 binary PSCs and PM6:L8-BO reference binary PSCs. [Display omitted] • Ternary PSCs are fabricate with blend of BTP-eC9 and IT-M as acceptor. • The improvement of charge dynamics process by ternary strategy. • The improved exciton dissocation between BTP-eC9 and IT-M. • The ternary PSCs with blend acceptor achieved a PCE of 17.31 %. [ABSTRACT FROM AUTHOR]

SnO 2 electron transport layers (ETLs) had an essential role in the n-i-p structure of perovskite solar cells. Improving the quality of the electron transport layer and enhancing interfacial contacts were key factors in the fabrication of high-performance perovskite solar cells. Therefore, a non-ionic polymeric polyacrylamide (PAM) modified SnO 2 colloidal solution with improved clustering of SnO 2 nanoparticles was presented to form a uniform and dense SnO 2 electron transport layer. The results demonstrated that no pinhole pores were found at the interface where the PAM-modified electron transport layer and the light absorbing layer came into contact, a structure that facilitated carrier transport and reduced carrier recombination at the interface location. Further beneficial effects were revealed by femtosecond Fs-TA measurements and trap of states (tDOS) analysis, where the carrier lifetime τ 2 decreased from 306.7 ps to 137.8 ps and the trap density of states of the film also decreased significantly. Correspondingly, the SnO 2 -PAM device exhibited an optimum efficiency of 21.61 %. Fantastic device stability was obtained due to the interaction of excellent contact at the SnO 2 /FAPbI 3 interface, and 85 % of the initial efficiency was maintained when placed in air for 1000 h for photo-aging tests, thereby improving the stability of FAPbI 3 grains. This method of improving the quality of tin oxide colloidal solutions provided a novel and simple way to prepare efficient perovskite solar cells. [ABSTRACT FROM AUTHOR]