The in situ fabricated perovskite nanocrystals (PNCs) obtained through spin-coating a precursor solution are suitable candidates to achieve efficient perovskite light emitting diodes (PeLEDs). In this work, the solvent effects of on-chip crystallization are investigated by correlating the nucleation and growth process of in situ fabricated formamidinium lead iodide (FAPbI 3 ) nanocrystals with their optical and electronic properties. The FAPbI 3 nanocrystals obtained from a precursor solution in γ-butyrolactone (GBL) are smaller than those obtained from N , N -dimethylformamide and dimethyl sulfoxide, and the relatively weak coordination between GBL and the precursor molecules enables reduced defect states in the resulted PNCs with enhanced photoluminescence properties. A modified LaMer model is proposed to describe the solvent effects in the on-chip crystallization process. Based on these understandings, red emissive FA 0.87 Cs 0.13 PbI 3 nanocrystal films with absolute photoluminescence quantum yields up to 70% are realized. Finally, an efficient PeLED with maximum luminance of 218 cd m −2 and peak external quantum efficiency of 15.8% is achieved with good reproducibility.
In this study, quasi-solid polymer electrolytes incorporating an ionic liquid (ILQSEs) fabricated in different organic solvents via a thermally-initiated polymerization strategy were investigated for flexible supercapacitors (SCs). It was found that low-viscous acetonitrile (AN) with a strongly-polar nitrile group was remained in the polymer matrix, which favored a higher ionic conductivity, wider electrochemical window, and better thermal stability of the ILQSE compared to its propylene carbonate (PC) counterpart. Moreover, the in situ polymerized quasi-solid electrolyte achieved close contact with the porous carbon electrode, accompanied by the favorable permeation of the IL into the electrode for enhancing the ion-transport kinetics and interface stability. Consequently, the as-assembled SC with the AN-based ILQSE delivered a high specific energy and specific power, excellent cycle stability, and reliable safety.
Flexible lithium–air batteries (LABs) with a redox mediator (RM) in the electrolyte demonstrate enhanced round-trip efficiency. However, their cycle performance is unsatisfactory due to severe corrosion of the Li metal anode. Herein, we propose a two step gelatinization strategy to fabricate a gradient RMs (including LiI, TMPD, and DMPZ) gel electrolyte, in which the bare electrolyte gelatinization on the Li surface and then the electrolyte contained RMs sequentially gelled on the formed gel. The RMs mainly distributed at the surface and anchored at the cathode side. By suppressing the shuttle of RMs in the electrolyte and alleviating the passivation of the Li anode, the mid-charging potentials can reach 3.44 and 4.08 V at the 15th cycle with and without the LiI mediator, respectively. The energy efficiency is 63% even at the 150th cycle, whereas the corresponding energy efficiency are only 47% and 51% for the LABs with liquid and normal gel electrolytes, respectively. Moreover, the cycle life of the battery containing the gradient gel electrolyte is three times longer than that with the liquid electrolyte. The gel electrolyte further offers the flexibility of the device, and the laminated cells thus fabricated can readily operate under harsh bending conditions.
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