Chen Li,Haoxuan Sun,Min Wang,Shan Gan,Da Dou,Liang Li
Perovskite solar cells offer great potential as a sustainable power source for distributed electronic devices that operate indoors. However, the impact of advanced lighting technology , especially the widely used pulse width modulation (PWM) technology, on perovskite photovoltaics has been ignored. Herein, for the first time in photovoltaics, we find that the light impact emitted by the PWM lighting system caused dynamic strain in perovskite thin films , induced phase separation, and accelerated the generation of metallic lead (Pb 0 ) defects, leading to irreversible degradation of the cell performance after 27 h ( T 80 ). To address this issue, formamidinium triiodide (FAI 3 ) is chosen to treat the surface of the perovskite and release residual stress, resulting in reduced lattice deformation during dynamic strain processes. Meanwhile, it suppresses harmful Pb 0 defects and reduces V oc loss at low light intensity . The champion device achieves impressive power conversion efficiency (PCE) of 35.14% and retains 99.5% of the initial PCE after continuous strobe light soaking for 2160 h.
A great hurdle restricting the optoelectronic applications of cesium lead halide perovskite (CsPbX3) nanocrystals (NCs) is due to the uncoordinated lead atoms (Pb0) on the surface, where most attempts to address the challenges in the literature depend on complicated post-treatment processes. Here we report a simple in situ surface engineering strategy to obtain highly fluorescent and stable perovskite NCs, wherein the introduction of the multifunctional additive 1-butyl-3-methyl-imidazolium tetrafluoroborate ([Bmim]BF4) can significantly eliminate the Pb0 traps. The photoluminescence quantum yield (PLQY) of the as-synthesized NCs was improved from 63.82% to 94.63% due to the good passivation of the surface defects. We also confirm the universality of this in situ passivation pathway to remove Pb0 deep traps by using fluoride acid-based ionic liquids (ILs). Due to the high hydrophobicity of the cations of ILs, the as-prepared CsPbBr3 NCs exhibit robust water resistance stability, maintaining 67.5% of the initial photoluminescence (PL) intensity after immersion in water for 21 days. A white light emitting diode (LED), assembled by mixing the as-synthesized CsPbBr3 NCs and red K2SiF6:Mn4+ phosphors onto a blue chip, exhibits high luminous efficiency (100.07 lm W−1) and wide color gamut (140.64% of the National Television System Committee (NTSC) standard). This work provides a promising and facile technique to eliminate the Pb0 traps and improve the optical performance and stability of halide perovskite NCs, facilitating their applications in optoelectronic fields.
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