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Synthesis and characterization of novel benzodithiophene-fused perylene diimide acceptors: Regulate photovoltaic performance via structural isomerism
摘要： Two isomeric benzodithiophene-fused perylene diimides, BPDI-1 and BPDI-2, are designed and synthesized via photo-induced ring-closure reaction between perylene diimide (PDI) acceptor and both isomeric benzodithiophene donor cores, including benzo[2,1-b:3,4-b']dithiophene (BDP) and benzo[1,2-b:4,3-b']dithiophene (BdT). The effect of structural isomerism on the molecular geometry, absorption, energy level, film morphology as well as photovoltaic performance is comparatively studied. It is found that the variation of the S atom substituted position in the donor cores results in distinct molecular geometries for the newly-developed BPDI-1 and BPDI-2 acceptors. Compared with BDP-containing BPDI-1, the incorporation of BdT core endows BPDI-2 with a remarkably enhanced backbone distortion. When blended with the commercially available polymer donor (PTB7-Th), such twisted structure feature for the BPDI-2 acceptor plays a key role in reducing molecule aggregation, which is helpful for the enhancements of short-circuit current density and photovoltaic efficiency effectively. As a result, non-fullerene solar cells fabricated from BPDI-2 acceptor achieve higher photovoltaic efficiency (4.44%) than that of BPDI-1 (2.98%), mainly benefited from superior short-circuit current density. This work provides us comparative understanding of isomeric geometry and device performance.
关键词： Benzodithiophene,Molecular geometry,Non-fullerene organic solar cells,Perylene diimide derivatives
更新于2025-11-19 16:56:42
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Fusion or non-fusion of quasi-two-dimensional fused perylene diimide acceptors: the importance of molecular geometry for fullerene-free organic solar cells
摘要： In this work, two small molecular electron acceptor (BT-FPDI and fBT-FPDI) comprising a central bithiophene (BT) bridge and two fused perylene diimide (FPDI) units were designed and synthesized for fullerene-free organic solar cells (OSCs). The molecular geometry of these electron acceptors can be adjusted through a locked conformation via photocyclization reaction. As expected, BT-FPDI has a highly twisted geometry with the assistance of the quasi-two-dimensional (quasi-2D) configuration of FPDI unit and modest dihedral angles between FPDI and BT units, while fBT-FPDI shows a relatively planar geometry with symmetrically aligned the FPDI wings. When pairing with polymer donor PTB7-Th, the intrinsic configuration characteristic of BT-FPDI guaranteed an impressive power conversion efficiency (PCE) of 8.07% with an open circuit voltage (Voc) of 0.81 V, and a recorded high short-circuit current density (Jsc) of 17.35 mA/cm2, which is almost the highest Jsc value reported in PDI-based fullerene-free OSCs. However, the optimal device employing fBT-FPDI as electron acceptor only delivered a PCE of 5.89% with a significantly reduced Jsc of 12.30 mA/cm2. The interesting result show that, unlike traditional PDI molecules, the ring-fusion molecular design has not produce the desired positive effect in FPDI derivatives, and also provide a new insight into the regulation of the molecular geometry based on FPDI acceptors with intrinsic quasi-2D structure.
关键词： perylene diimide,molecular geometry,fullerene-free organic solar cells,ring-fusion,power conversion efficiency
更新于2025-09-11 14:15:04
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Dihydrophenazine‐based double‐anchoring dye for dye‐sensitized solar cells
摘要： A novel dihydrophenazine-based organic di-anchoring dye DK-11 was synthesized by utilizing a simple synthetic protocol. The dye was characterized by optical and electrochemical studies and used as a sensitizer for dye-sensitized solar cell. The proposed butterfly structure was supported by IR experiments which ensured the binding of both carboxylic acid units on the semiconductor surface. Using the dye DK-11, the device generated an efficiency of 5.07% with JSC, VOC, and FF values of 10.65 mA/cm2, 0.67 V, and 0.71, respectively.
关键词： donor-acceptor dyes,dye-TiO2 binding,molecular geometry,di-anchoring dyes,dye-sensitized solar cells
更新于2025-09-11 14:15:04
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Crystal growth, Hirshfeld surface analysis, DFT study and third order NLO studies of Thiourea 4 dimethyl aminobenzaldehyde
摘要： In this work we investigate the crystal growth and the characterization of Thiourea 4 dimethyl aminobenzaldehyde (TDA) crystal. The Molecular geometry shows good agreement with Experimental and Theoretical (HF and DFT) bond lengths and bond angles. From X-ray diffraction studies it shows that the structure belongs to monoclinic structure and experimental, refinement data also discussed. Hirshfeld surface analysis used to clarify the intermolecular interactions in a visual manner. Vibrational assignments of TDA crystal is discussed by FT-IR and FT-Raman spectroscopic studies. The assignments are compared with Density Functional Theory calculation and it shows good agreement with experimental data. The Frontier molecular orbital energy gap is found by TD-DFT method with HOMO-LUMO calculation. The Third order NLO studies for TDA organic crystal is done by Z-scan technique and Optical parameters like Non linear and Linear refractive index are calculated.
关键词： Z-scan Technique,DFT,Hirshfeld surface analysis,X-Ray diffraction,Molecular Geometry.
更新于2025-09-10 09:29:36