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junction solar cell technologies [4]. The great majority of QD-
IBSC prototypes created up until this point have utilized type -
I QDs. Many materials have a two-step absorption mechanism,
including the InAs/GaAs QD system [5], GaAs/AlGaAs [6],
and InAs/AlGaAs [7], has been extensively studied experi-
mentally. Recently, one single InAs/GaAs QD with the same
method was reported [8–12]. The most crucial characteristic
that provides measured energy levels is the quantum effect.
This type of material’s dimensions and form can be altered
to customize its electrical and optical characteristics. The
distinction between these sorts is the quantity of the limited
directions. Utilizing quantum dot solar cells is one of the
strategies used most frequently to improve the effectiveness of
photovoltaic conversion in solar cell technology. among the
most energetic study areas when it comes to third-generation
solar cells at the moment is quantum dot solar cells. When
compared to a quantum well, a quantum dot has stronger
3-dimensional quantum confinement effects [13].
II. THE LITERATURE REVIEW
V. Aroutiounian created the p-i-n quantum dot model in 2001.
To enhance the current, Inside the i-layers, he produced several
layers of quantum dots. Quantum confinement phenomenon
quantizes the energy level in quantum dots, which has been
crucial to understanding quantum dots [14]. It would seem
fair to think about whether a low dimensional structure, such
a quantum dot p-i-n structure, could offer a fresh method
for solving the challenge of high-efficiency solar cells [15].
These solar cells’ drawbacks include inter dot gaps’ effects
on electrical states, transportation properties, array shape, or- d2E = q(p - n + ND+ - NA-)/e (3)
der and disorder, and quantum dot orientation [16]. Actually,
the existence of very few atoms in a quantum dot, where
excites are restricted to a considerably smaller space on the
order of the exciting Bohr radius of the material, which causes
quantum confinement. Charge carriers (holes and electrons)
are quantum-confined in the variable-size quantum dots that
make up the i-layer, which increases the material’s effective
band gap [17]. Numerous studies have focused on type-I
InAs/GaAs QD solar cells, which can extend the spectral re-
sponse to longer wavelengths beyond the GaAs absorption
edge [18, 19]. The type-I QDs feature strong carrier recom-
bination in addition to high optical absorption due to the
significant electron-hole wave function overlap. Nanoscale
solar cells consisting of various components and structures
have been the subject of numerous studies, with a variety of
study findings being given. The behavior of nanoscale and
faults in this category of substances have been the subject of
numerous investigations, however the highest converted with
a documented efficiency of manufactured nanoscale solar cell
has only been 19.4%, it has two times of illumination [20].
The shapes of the inter-dot space, the cubic, spherical, and
Ahmed, Alsaif & Algwari
cylindrical dots, as well as the alloy composition, are taken
into consideration as we analyze the behavior of various char-
acteristics and features of a multiple quantum dots solar cell
(MQDSC) structure in this work [21].
III. RESEARCH METHODOLOGY
A. Mathematic Theory Approach
Basic semiconductor equations had to be solved in order to
assess the performance of the solar cell; these equations have a
real-valued function. The following equations, which explain
the physical models utilized for this simulation, can be used
to describe solar cell operation [22]:
The Poisson equation, which connects charge to electrostatic
potential, is the governing equation. Equation (1) contains the
Poisson Electrostatic Potential equation [23].
d2E (1)
dx2 = ?/e
where rho being the charge density (C.cm-3), and epsilon is
the substance permittivity. Equation (2), which is derived
from the charge neutrality equation, can be written as the
dopant fully ionized.
? = q(p - n + ND+ - NA-) (2)
Equation (2) yields equation (3) when it is combined with
equation (1) [23]
dx2
The second equation is a continuity equation, which is also
known as a governing equation because it considers genera-
tion, recombination, drift, and diffusion simultaneously. The
continuity equation for the change in electron and hole con-
centration is represented by equations (4) and (5) [23]:
?n = Gn - Rn + 1. ? Jn (4)
?t q ?x
?p = Gp - Rp + 1. ? Jp (5)
?t q ?x
Where the current density of the electrons is Jn, while the
current density of the holes is Jp, Gn and Gp represent the
rates of creation of electrons and holes, respectively, and Rn
and Rp represent the rates of recombination of electrons and
holes.
In semiconductors, electric currents are produced as a result
of the movement of charges by electrons and holes. A solar