Designing Three‐dimensional (3D) Non‐Fullerene Small Molecule Acceptors with Efficient Photovoltaic Parameters

Abstract

Three dimensional (3D) acceptor‐donor‐acceptor (A−D‐A) type small molecules (M1, M2, M3 and M4) are theoretically investigated for optoelectronic properties. The designed molecules contain spirobifluorene as core unit linked with end capped acceptors through four four thieno‐[3,2‐b]Thiophene (TT) units. The end capped acceptors are (3‐methyl‐2‐thioxothiazolidin‐4‐one) (M1), 2‐(2‐ethylidene‐5,6‐difluoro‐3‐oxo‐2,3‐dihydroinden‐1‐ylidene)malononitrile (M2), 2‐(3‐ethyl‐4‐oxothiazolidin‐2‐ylidine)malononitrile (M3) and 2‐(2‐ethylidene‐5,6‐dicyano‐3‐oxo‐2,3‐dihydroinden‐1‐ylidene)malononitrile (M4). The photovoltaic parameters of the designed molecules are compared with the recently reported reference compound R. Among all designed molecules, M4 is a low energy gap material (2.28 eV), broad absorption which is attributed to excellent communication between strong electron withdrawing end capped acceptors through extended conjugation. All newly designed molecules have lower binding energy as compared to reference molecule R which results in higher exciton dissociation in excited state. The reorganization energy calculations indicate good charge transfer ability of the designed molecules. M4 shows the lowest λe (0.0022) value with respect to the reference molecule R (0.034) which signifies its enhanced electronic transport behavior. The calculated open circuit voltages (Voc) ranges from 1.97 to 2.36 eV, 2.11 to 2.49 eV and 1.9 eV to 2.28 eV with respect to three different well known donor materials PTB7‐Th, PBDB−T and P3HT, respectively.

Designing indacenodithiophene based non-fullerene acceptors with a donor–acceptor combined bridge for organic solar cells

“…The transition density matrix enables us to evaluate: (i) the interaction between the donor and acceptor moieties with each other in the excited state; (ii) the electronic excitation; and (iii) the electron hole localization. 58 To study it, we divided our molecules into D (donor core unit), B (combined bridge group), and A (end capped acceptors) parts. It is clear from the TDM diagrams (Fig.…”

Designing triazatruxene-based donor materials with promising photovoltaic parameters for organic solar cells

“…TDMs method is a key point which enables us to estimate the (i) electron hole localization; (ii) electronic excitation and (iii) excited state interaction among acceptor and donor units. 67 To study these effects, we divided our reference R and designed molecules M1-M5 into three segments namely; donor (D), p-bridge (B) and acceptor (A). The TDMs diagrams indicate that reference R and M3 molecules exhibit similar behaviour in which electron coherence is partially available on the diagonal of donor, more on the bridge segment and mostly present on the end-capped acceptor moieties.…”

A DFT study to probe homo-conjugated norbornylogous bridged spacers in dye-sensitized solar cells: an approach to suppressing agglomeration of dye molecules

“…Spirobiuorene has been used to design three-dimensional solar cells to prevent agglomeration of the dye molecules by modulating the acceptor groups to optimize PCE. [23][24][25][26][27] In this work, we report a new spacer to avoid the p-p aggregation of dye sensitizer molecules in DSSCs. The p spacer units have been replaced with the rigid s-homo-conjugated framework.…”

“…To support the FMO diagram, the total density of states and partial density of states (PDOS) have been calculated for all the studied dyes in CAM-B3LYP/6-31G(d) in THF using the CPCM solvent model. [23][24][25] The studied dye molecules (1-6) have been divided into three parts donor, spacer and acceptor units (Scheme 2). In PDOS spectra distribution pattern of donor, spacer and acceptor units are represented by red, green and blue lines, respectively (Fig.…”

“…50 Transition density matrix estimates the nature of transition and the TDM map can be employed to probe the possibility of excitation escaped from coulomb attraction. [24][25][26][27] The TDM absorption and emission are computed for S1 state in the same environment. TDM method is important to estimate electronic excitation interaction between different parts of dyes in excited state and hole localization.…”