Small-molecule (SM)-based
organic solar cells (OSCs) have dominated
the photovoltaic industry on account of their efficient optical and
electronic properties. This quantum mechanical study addresses a DFT
study of pentacyclic aromatic bislactam (PCL)-based small molecules
for extremely proficient OSCs. Five novel small molecules (
PCLM1–PCLM5
) retaining the A−π–A−π–D−π–A−π–A
arrangement were fabricated from the reference
PCLR
.
At the MPW1PW91/6-31G** level of theory, detailed profiling of these
novel molecules was performed by accurately following DFT, along with
the time-dependent density functional theory (TD-DFT) hypothetical
simulations to analyze the UV–visible absorption (λ
max
), light-harvesting efficiency (LHE), dipole moment (μ),
fill factor (FF), open-circuit voltage (
V
OC
), power conversion efficiency (PCE), frontier molecular orbitals
(FMOs), binding energy (
E
b
), density of
states (DOS), electrostatic potential (ESP), and transition density
matrix (TDM) plots. Alteration of peripheral acceptors in all of the
molecular structures drastically modified their charge-transfer properties,
such as a strong light-harvesting capability in the range of 0.9993–0.9998,
reduced exciton
E
b
(from 0.34 to 0.39
eV), a reduced bandgap (
E
g
) in the range
of 1.66–1.99 eV, an elevated λ
max
(775–959
nm) along with a higher μ in the solvent phase (1.934–7.865
D) when studied in comparison with
PCLR
, possessing an
LHE of 0.9986, an
E
b
of 0.40, an
E
g
2.27 eV, λ
max
at 662 nm,
and a μ of 0.628 D. The FMO analysis revealed the uniform dispersal
of charge density entirely along the highest occupied (HOMO) and
lowest unoccupied (LUMO) molecular orbitals in newly constructed
moieties. Electron as well as hole mobility rates,
V
OC
, FF, and PCE of all novel molecules
(PCLM1–PCLM5)
were higher as compared with those of
PCLR
, ultimately
making them exceptional candidates for solar devices. Focusing on
the outcomes, terminal acceptor modification was found to be a suitable
method for the development of highly tuned OSCs in the future.