Tin‐based perovskite solar cells (TPSCs) are attracting intense research interest due to their excellent optoelectric properties and eco‐friendly features. To further improve the device performance, developing new fullerene derivatives as electron transporter layers (ETLs) is highly demanded. Four well‐defined regioisomers (trans‐2, trans‐3, trans‐4, and e) of diethylmalonate‐C60 bisadduct (DCBA) are isolated and well characterized. The well‐defined molecular structure enables us to investigate the real structure‐dependent effects on photovoltaic performance. It is found that the chemical structures of the regioisomers not only affect their energy levels, but also lead to significant differences in their molecular packings and interfacial contacts. As a result, the devices with trans‐2, trans‐3, trans‐4, and e as ETLs yield efficiencies of 11.69%, 14.58%, 12.59%, and 10.55%, respectively, which are higher than that of the as‐prepared DCBA‐based (10.28%) device. Notably, the trans‐3‐based device also demonstrates a certified efficiency of 14.30%, representing one of the best‐performing TPSCs.
Based on the quantum mechanics and molecular mechanics (QM/MM) method, theoretical studies reveal the aggregation effect induced TADF mechanism for a 4,4′-(6-(9,9-dimethylacridine-10(9H)-yl)quinoline-2,3-dibenzonitrile (DMAC-CNQ) emitter.
The investigations on the relationship between geometrical structures, excited state properties, and photophysical performance can accelerate the design of thermally activated delayed fluorescence (TADF) molecules. Herein, the photophysical properties of newly proposed organic TADF molecule: [4‐(9,9‐dimethyl‐9,10‐dihydroacridine) phenyl] (pyridin‐4‐yl)‐methanone (PyB‐DMAC), are theoretically investigated by using the quantum mechanics and molecular mechanics method. The photophysical performance dependency of PyB‐DMAC molecule on its geometrical and electronic structures, and aggregation effects are systematically analyzed. The calculated fluorescence quantum efficiencies are in good agreement with the experimental results, for instance, the calculated fluorescence efficiency of 61.2% (exp. 49%) for PyB‐DMAC molecule in the crystal phase. Based on these investigations, novel organic TADF molecules can be designed by balancing the singlet–triplet energy gap (ΔEST) and transition dipole moment. Sixteen unexplored candidates are screened with similar structures to PyB‐DMAC molecule, while two new TADF organic molecules (PyBF‐DMAC and OSOF‐DMAC) are selected with enhanced luminescence performance. The newly designed TADF molecules reveal lower reorganization energies and reduced nonradiative decay rates. The simulation results exhibit that their luminescence quantum efficiencies in toluene solvent and amorphous state are as high as 63.7%, 53.2% and 90%, 97.4%, respectively.
Organic donor-acceptor (D-A) type thermally activated delayed fluorescence (TADF) materials exhibit high luminous quantum efficiencies and therefore attract considerable research interests as organic light-emitting diodes (OLEDs). Accurately calculating the photoluminescence...
The certified power conversion efficiency of perovskite solar cells gradually approaches to that of crystalline silicon solar cells. With the advantages of improved thermal stability and environmental friendliness, lead-free all...
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