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Designing alkoxy-induced based high performance near infrared sensitive small molecule acceptors for organic solar cells
摘要： Scientist are dedicated to design and synthesize efficient photovoltaic materials to overcome the energy crises. In this regard, herein, we have designed four new small acceptor molecules namely (A1, A2, A3 and A4) for better performance in organic solar cells. These molecules consist Alkoxy-Induced Naphtho-dithiophene core unit flanked with 2,2-ethylidene-5,6-dicyano-3-oxo-2,3-dihydroinden-1-ylidene-malononitrile (A1), methyl-2-cyano-2,2-ethylidene-5,6-difluoro-3-oxo-2,3-dihydroinden-1-ylidene-acetate (A2), 5,2-ethylidene-5,6-difluoro-3-oxo-2,3-dihydroinden-1-ylidene-3-methyl-2-thioxothiazolidin-4-one (A3) and 2,5-ethylidene-6-oxo-5,6-dihydrocyclopenta-thiophen-4-ylidene-malononitrile (A4) end-capped acceptor groups. Their optical, electrical and geometries have been compared with reported molecule R. Frontier molecular orbital diagram reveal excellent charge transfer rate, The electron density is shifted from donor to acceptor unit. Among all, A1 exhibits the highest absorption in the visible region (λmax) at 798 nm in chloroform solvent. The maximum open circuit voltage (2.08 V) is observed for A3 when blended with PTB7-Th donor polymer. All studied molecules have high charge mobilities due to lower reorganization energy values with respect to model molecule R. A1 has the highest electron mobility among all molecules due to lower value of reorganization energy which is 0.0034. Furthermore, all designed molecules show good Solubilities in organic solvent. A2 exhibit high value of dipole moment which reveal good solubilities in fabrication process.
关键词： Transition density matrix,Non-fullerene acceptor,Open circuit voltages,Naphtho-dithiophene,Reorganization energy,Fused ring electron acceptor
更新于2025-09-19 17:13:59
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Tuning opto-electronic properties of alkoxy-induced based electron acceptors in infrared region for high performance organic solar cells
摘要： Limitations of fullerene-based acceptors for organic solar cell have driven the scientific community to design and synthesize non-fullerene acceptors. In this regard, we have designed four new molecules designated here S1-S4 containing Alkoxy-Induced Naphtho-dithiophene donor unit and 2-(5,6-difluoro-2-methylene-3-xo-2,3-dihydrinden-1-ylidene)malonoitrile acceptor moiety attached with different bridge units. The electronic and optical properties of the designed molecules S1-S4 are compared with the recently reported reference molecule R. The bridge units are, thiophene (S1), 2-fluorothiophene (S2), 2-(thiophe-2-yl)thiophene (S3) and 2-(4-fluorothiophen-2-yl)thiophene (S4). The designed molecule S3 shows absorption maximum in near infra-red (NIR) region at 830.0 nm and 910.6 nm in gas phase and chloroform solvent, respectively. The energy gaps of designed molecules are lower than that of the reference R, which reveal high charge transfer for the designed molecules. Among all, S3 has the lowest energy gap (1.68 eV). Open circuit voltages (Voc) calculation are performed with well-known PTB7-Th donor. Voc of all the molecules are higher than R where the maximum Voc of 1.92V is calculated for S2. Low reorganization energies of our designed molecule reflect high charge transfer rate with respect to R. Among all designed molecules, S3 has the highest electron mobility.
关键词： Alkoxy induced,Reorganization energy,Transition density matrix,Non-fullerene acceptor,Thiophene,Charge Transfer,Open circuit voltages
更新于2025-09-19 17:13:59
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Tuning Optoelectronic Properties of Dithienopyrrole Donor Molecules for Organic Solar Cells
摘要： Theoretical analysis of physical properties of organic solar cells (OSCs) are important in order to reveal the correlation between power conversion efficiencies (PCE), structure and properties. Five new A?D?A type small molecules M1, M2, M3, M4, and M5 were designed by using dithienopyrrole (DTP) as electron rich donor unit with different types of π-spacers and end capped acceptor units. Functional MPW1PW91/6-31G(d,p) level of theory was used to optimize the geometry of all molecules. For excited state calculation TD-MPW1PW91/6-31G(d,p) level of theory was used. The geometries, electronic structures, dipole moment, open circuit voltage, reorganization energies and charge transport properties of designed molecules (M1 M5) have been scrutinized comparing with the reported compound R. The results revealed that the HOMO energy levels of molecules M1, M2, M3, and M5 were lower while M4 was of high energy level thus facilitate the donation of electron as compared to references molecule R. While LUMO energy level of all the molecules were slightly high energy due electron withdrawing effects of spacer and acceptor moiety. Highest energy gap of HOMO–LUMO was observed in M1 which was 2.48 eV and M3 showed low energy gap (2.11 eV) as compared to other designed molecules. All molecules showed low values for λe, so they have high rate of electron transfer as compared to R. All designed molecules exhibited higher value of dipole moment as compared to reference molecule R except M1. Higher value of dipole moment of donor molecules contrary to reference means good solubility towards organic solvents which is beneficial for further solar cell device fabrication. All designed molecules show higher Voc values except M4 which has comparable Voc with respect to reference molecule R. In short, choice of appropriate electron withdrawing and donating groups is very important for improving power conversion efficiencies of OSCs.
关键词： Dithienopyrrole,reorganization energy,open circuit voltages,density of states,density functional theory
更新于2025-09-12 10:27:22