An electron-transport layer with appropriate energy alignment
and
enhanced charge transfer is critical for perovskite solar cells (PSCs).
In addition, interface stress and lattice distortion are inevitable
during the crystallization process of perovskite. Herein, IT-4F is
introduced into PSCs at the buried SnO2 and perovskite
interface, which assists in releasing the residual stress in the perovskite
layer. Meanwhile, the work function of SnO2/IT-4F is lower
than that of SnO2, which facilitates charge transfer from
perovskite to ETL and consequently leads to a significant improvement
in the power conversion efficiency (PCE) to 23.73%. The V
OC obtained is as high as 1.17 V, corresponding to a low
voltage deficit of 0.38 V for a 1.55 eV bandgap. Consequently, the
device based on IT-4F maintains 94% of the initial PCE over 2700 h
when stored in N2 and retains 87% of the initial PCE after
operation for 1000 h.
To improve the performance of perovskite solar cells (Pero‐SCs), a betaine‐based zwitterionic polymer poly(sulfobetaine methacrylate) (denoted by PSBMA) is employed as interlayers at both the anode and cathode in p‐i‐n Pero‐SCs. 1) At the anode side, PSBMA acts as a glue to stitch the two interfacially unfavorable materials: perovskite and poly(bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine), by which the quality of perovskite films as well as the corresponding device performance greatly improve. 2) At the cathode side, PSBMA smoothes the energy levels between PC61BM and Al, and thus facilitates the electron injection efficiency. The power conversion efficiency (PCE) is promoted from 17.31% to 19.16% after PSBMA is introduced as both anode and cathode sides of the p‐i‐n Pero‐SCs. More importantly, PSBMA also shows great potential for large active area (1 cm × 1 cm) Pero‐SCs, and a PCE as high as 15.7% is achieved.
All‐inorganic perovskite CsPbI3 contains no volatile organic components and is a thermally stable photoactive material for wide‐bandgap perovskite solar cells (PSCs); however, CsPbI3 readily undergoes undesirable phase transitions due to the hygroscopic nature of the ionic dopants used in commonly used hole transport materials. In the current study, the popular donor material PM6 in organic solar cells is used as a hole transport layer (HTL). The benzodithiophene‐based backbone‐conjugated polymer requires no dopant and leads to a higher power conversion efficiency (PCE) than 2,2′,7,7′‐tetrakis[N,N‐di(4‐methoxyphenyl)amino]‐9,9′‐spirobifluorene (Spiro‐OMeTAD). Moreover, PM6 also shows priorities in hole mobility, hydrophobicity, cascade energy level alignment, and even defect passivation of perovskite films. With PM6 as the dopant‐free HTL, the PSCs achieve a champion PCE of 18.27% with a competitive fill factor of 82.8%. Notably, the present PCE is based on the dopant‐free HTL in CsPbI3 PSCs reported thus far. The PSCs with PM6 as the HTL retain over 90% of the initial PCE stored in a glovebox filled with N2 for 3000 h. In contrast, the PSCs with Spiro‐OMeTAD as the HTL maintain ≈80% of the initial PCE under the same conditions.
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