Table 1 Electronic bandgaps computed using DFT and Macroscopic static dielectric constant (\(\varepsilon\)) computed using density functional perturbation theory (DFPT) and BSE for PE, PET, PCPDT-BT, PCPDT-TTQ, PCPDT-TQ, and PCPDT-BBT.

From: Electronic properties and optical spectra of donor–acceptor conjugated organic polymers

 

Electronic Bandgap (eV)

Optical gap (eV)

Static dielectric constant (\(\varepsilon\))

(Expt.)\(^i\)

Octamer (y\(_0\))

1D

3D (Occ)

(Expt)\(^{ii}\)

BSE

DFPT

(Expt.)\(^{iii}\)

B3LYP

B3LYP

HSE06

PE

–

5.28 (0.0)

9.89

8.10

8.8

1.84

2.87

2.25

PET

–

5.11 (0.0)

5.28

4.13

4.0

1.56

2.36

\(\sim\) 3.5

PCPDT-BT

1.81

1.44 (0.0)

1.78

0.85 (0.0)

1.44

8.82

12.40

3.6

PCPDT-TTQ

0.80

0.80 (0.98)

0.88

0.60 (0.0)

\(\sim\) 0.46

5.49

8.99

–

PCPDT-TQ

0.6

0.77 (0.91)

0.36

− (0.67)

0.30

10.18

14.62

–

PCPDT-BBT

–

0.88 (1.00)

1.18

− (1.00)

–

13.73

32.04

–

  1. For octamers, the computations are carried out using B3LYP at 6-31G(d,p) level. The occ in the parenthesis represents the probability amplitude of finding an electron which is the electron occupancy in the conduction band minimum level. \({^i}\), \(^{ii}\), and \(^{iii}\) represent an experimental electrochemical gap in the solution phase, absorption onsets from crystalline/thin films, and known experimental dielectric constant, respectively14,33,37,45,46,47,48,49,50.
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