Inverted perovskite solar cells (PSCs) with PEDOT:PSS as hole transporting layers exhibit tremendous prospects for flexible photovoltaic applications owing to their characteristics of low-temperature solution processability and favorable flexibility. Nevertheless, the energy level mismatch of PEDOT:PSS and perovskite layer results in a severe energy deficit. In addition, the acidity of PEDOT:PSS is detrimental to the stability of devices. To address these issues, we employ a glyceryl monostearate (GMS) interlayer to improve the work function and conductivity of PEDOT:PSS. Meanwhile, it can passivate the traps at the interface of PEDOT:PSS/perovskite. As a consequence, the champion power conversion efficiencies of photovoltaic devices based on MAPbI 3 films increase from 14.82% to 17.29% due to the surface modification of PEDOT:PSS with GMS, which is mainly ascribed to the enhanced open-circuit voltage and short-circuit current density. Furthermore, the nonencapsulated MAPbI 3 perovskite films and devices based on GMS-modified PEDOT:PSS show much better moisture stability and thermal stability than the counterparts without GMS modification.

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High-quality perovskite films with large grains and reduced surface defects were obtained via an inverted annealing process. Corresponding photovoltaic devices achieved a highest efficiency of 20.4% with a stabilized power conversion efficiency (PCE) of 19.8%.

Fabricating compressive-strained perovskite films can boost the efficiency and stability of perovskite solar cells (PSCs). However, compositional engineering toward the conversion of surface tension strain to compressive strain rarely succeeds. Herein, we propose an effective lattice-matching chelation strategy to modulate the strain of the crystal lattice of perovskite films. Detailed investigations show that the organic salt of bidentate imidazole (MZ-1) can firmly anchor the perovskite lattice, resulting in compressive-strained perovskite films, leading to better energy alignment, improved charge carrier transport, decreased nonradiative recombination, and lower trap state density. PSC based on MZ-1 exhibits a dramatically improved efficiency of 24.61% along with improved long-term thermal stability. Importantly, a largearea (25 cm 2 ) integrated module achieves an efficiency of 20.53%.

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