The non-radiative energy loss in perovskite solar cells (PSCs) is a key factor that limits full potential of photovoltaic performance to values below the Shockley–Queisser limit. Herein, we report a...
A high-quality
perovskite film is a key aspect contributing to
high photovoltaic performance of all-inorganic perovskite solar cells.
We herein demonstrate that the addition of methylammonium iodide (MAI)
influences effectively both the tailored film morphology and precise
crystal growth to construct high-quality CsPbI2Br films.
It is found that an MAI additive retards the crystallization kinetics
to control the inorganic perovskite films to form a highly crystalline
α-CsPbI2Br structure consisting of microsized grains
with reduced defect density. The optimal MAI additive (10 wt %) achieves
a power conversion efficiency (PCE) of 10.40% for the CsPbI2Br-based all-inorganic perovskite solar cells, which is >30% enhancement
from 6.95% of the pristine one. The solar cells employing the MAI
additive possess high operational and thermal stability, retaining
>70% of the original PCE after aging for 1500 h in ambient atmosphere
and under continuous heating at 85 °C for 30 h, respectively.
The photovoltaic performance with an indoor light source was also
examined using a white light-emitting diode (6500 K, 1000 lux), showing
promising PCEs of 23.51% with a stabilized power output of 21.15%.
Further optimization of perovskite light‐emitting diodes (PeLEDs) is impeded by crystal deformation caused by residual stress and defect formation with subsequent non‐radiative recombination. Molecular additives for defect passivation are widely studied; however, the majority have insulating properties that hinder charge injection and transport. Herein, highly efficient green‐emitting PeLEDs are reported by introducing semiconducting molecular additives (Fl‐OEGA and Fl‐C8A). Transmission electron microscopy shows that conjugated additives exist primarily at the grain boundaries of perovskite, and Kelvin probe force microscopy confirms that the variation in contact potential difference between grain boundaries and perovskite crystal domains is significantly reduced. The residual tensile stress is reduced by 13% and the activation energy for ion migration increases in the Fl‐OEGA‐treated perovskite film, compared to those of the film without additives. Compared to insulating 2,2′‐(ethylenedioxy)diethylamine (EDEA), the introduction of semiconducting additives prevents a significant reduction in the charge‐transport capability. Furthermore, the PeLEDs with Fl‐OEGA show a negligible shift in the turn‐on voltage and a significantly smaller decrease in the current density with increasing Fl‐OEGA compared to the devices with EDEA. Finally, the 3D CsPbBr3–PeLEDs show the highest external quantum efficiency of 21.3% by the incorporation of semiconducting Fl‐OEGA as a new multifunctional additive.
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