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Influence of Different Spherical Binary Plasmonic NPs on HTM Layer in Methyl Ammonium Lead Triiodide Solar Cell
Cliff Orori Mosiori Walter Kamande Njoroge Lawrence Otieno Ochoo 1
1 Kenyatta University
P. O. Box 43844-00100, Nairobi, Kenya
DOI: 10.22178/pos.50-4
LCC Subject Category: TP155-156
Received 03.09.2019 Accepted 27.09.2019 Published online 30.09.2019
Corresponding Author: Cliff Orori Mosiori corori@tum.ac.ke
© 2019 The Authors. This article is licensed under a Creative Commons Attribution 4.0 License
Abstract. Methylammonium lead triiodide perovskite solar cells have attracted huge research interest. Its optoelectronic properties are competing with those of silicon wafers. It is a hybrid absorber with a direct band gap of about 1.53 eV with good light-absorption capability appropriate for optoelectronic applications. A typical perovskite solar cell HTML layer rarely incorporates ZnO or Cu2O or TiO2 nanoparticles to increase charge carrier transport. These ZnO, Cu2O, TiO2 nanoparticles can be introduced into the HTM layer to modify its PSCs efficiency and performance. These nanoparticles are direct band gap binary semiconductors with a wide band gap energy range of 2.17 eV to 3.37 eV respectively which can lead to higher transport mobility and enhanced HTM nanostructured layer. In this paper, two model solar cell having a ITO/TiO2/CH3NH3Pbl3/P3HT/Ag and ITO/TiO2/Ag:CH3NH3PbI3/P3HT/Ag structures were proposed, geometrically modelled and simulated using SCAPS-1D software. Their HTM layer (composed of P3HT) was doped with ZnO, Cu2O, and TiO2 nanoparticles respectively to determine their influence on PCEs of this solar cells. It was revealed that starting from undoped P3HT layer all through the Cu2O, ZnO to TIO2 doped layers, efficiency reduced from 13.123 % and 9.071% respectively; fill factor (FF) also reduced from 69.4% to 48.9 % for the doped CH3NH3PbI3 perovskite solar cell while efficiency of doped CH3NH3PbI3 perovskite solar cell reduced from 13.033 % and 9.091%, the fill factor (FF) also reduced from 66.4% to 52.9 % respectively. It was noted that the solar cell employing P3HT undoped layer had the best performance and concluded that introducing nanoparticles onto P3HT layer has a negative impact on the performance of CH3NH3PbI3 perovskite solar cell.
Keywords: Plasmonic Oscillations; hybrid perovskite; SCAPS-1D software; photon absorption; Computer Simulation Technology.
INTRODUCTION
Modern thin-film solar cells have reduced material consumption [2] and fabrication costs. However, a major limitation facing hybrid perovskite thin-film solar cells is its poor photon absorption [1]. It is documented that light-trapping can be increased by increasing the optical path length inside a film, but how to implement it remains a mirage [4]. Plasmonic structures can modify the excitations of localized surface plasmon to improve photon absorption [5]. Surface plasmon is a collective oscillation of free exciting electrons of metallic nanoparticles [5, 7, 9] which can be used to enhance optical absorption through scattering and near-field concentration photons depending on particle shape [11], size [15], inter-particle distance [22], optical resonance [25], material nature [34] and type of coupled systems avail-
able [29]. However, plasmon coupling only occurs when closely spaced nanoparticles have their associated electron oscillations influencing its local field affect electron oscillations of neighbouring particles [28, 31, 33]. Many noble metallic nanoparticles have been tested for plasmonic coupling. These include gold (Au), copper (Cu), silver (Ag) and aluminium (Al) nanoparticles [9, 12, 18]. Their dipole and quad-rupole plasmon resonances can be described qualitatively using spherical nanoparticles [20, 26]. They have already shown a red-shift in total absorption flux enhancement and tunable localized surface plasmon resonance. The role of near-field coupling, resonance, scattering and transmission of light have been investigated too using Ag nanoparticles [6, 11, 27]. An enhancement factor of 2.3 in external quantum efficiency
at 1100 nm wavelength, a sevenfold enhancement of light absorption and a 16-fold enhancement for 1250 nm using Ag nanoparticles have been reported by some publications [14, 18, 25, 33]. This paper focuses on the doping the HTM layer and its influence on the efficiency of methylammonium lead triiodide solar cells as simulated using SCAPS-1D software at AM1.5G solar radiation that employs FDTD, FEM, and FIT methods.
SCAPS-1D simulation software. SCAPS-1D is a one-dimensional solar cell simulation software that employs three coupled differential equations. The first equation is the Poisson's equation given as (1):
d ( d<p , _ te 1 J -
dx f
P(x) - n00 - Nd(x) - Na(x) + +PtOO — nt(x)
(1)
where ^ is electrostatic potential, q is electron charge, p is free holes, n is free electrons, pt is trapped holes, nt is trapped electrons, Na- is ionized acceptor-like doping concentration, and Nd+ is ionized donor-like doping concentration [24, 30].
Computer Simulation Technology. Computer Simulation Technology (CST) is a 3D simulation software used to numerically calculate optical properties required for many applications that include plasmonic solar cells, electromagnet metamaterials and antennas when exposed to an electromagnetic field. It is a 3D EM solver that solves Maxwell's equation in the time domain with Finite integration method (FIT) and frequency domain with the Finite element method (FEM) by incorporating FDTD and FDFD techniques. CST software is a Multiphysics software that employs FIT, FEM, FDTD and FDFD to simulate designed plasmonic nanostructures of various PV devices. CST is a 3D simulation software used in order to attain accurate simulation results under the absorption profile and internal quantum efficiency as a function spatial position, photon density and frequency. It employs FDTD technique to evaluate electron transport, series resistance and fill factor enhancement, distribution profile of the photons absorbed and also electron-hole pair recombination rate. It is a time domain technique used to solve Maxwell's equations in differential form over a grid-based domain in a single simulation by calculating electric field, E, and magnetic field, B for time irrespective of the designed 1D, 2D and 3D models expressed as [14, 15, 23]:
The second equation (2) is the continuity equation for holes as [2, 5, 11]:
dpn pn - pno dÇ
Up PnMp
dt
dx
dpn
dx + DP aS
(2)
while the 3 equations is the continuity equation for electrons as:
dnv dt
nr
n
po
-Gn~
Ln
^n' dx n dx2
Tip [J.n
dÇ dx
(3)
where G is generation rate, % is permittivity while D is the diffusion coefficient.
j-tB(R,t) = -VxE(R,t)-Jm(R,t)
(4)
ytD(R,t) = VxH(R,t)-Je(R,t)
(4)
It reveals nano-structural shapes, material types, dielectric environments, array pitches and particle locations for the source of light scattering. Its optical computational power provides the final power conversion efficiency of plasmonic solar cells. FEM available in CST software and it is used to calculate solutions to partial differential and integral Maxwell's equations. It is suitable for simulating irregular shaped geometrical models for optical devices as it provides information even of large dtime and frequency domains small elements in regions where fields may abruptly change. It can also simulate larger elements in less important and unexpected electromagnet regions.
METHODOLOGY
Device Structures. A plasmonic model solar cell was designed containing silver nanoparticle doped and undoped methylammonium lead triiodide (CH3NH3PM3) as a perovskite absorber layer. The solar cell had five layers as a glass cover (protection purposes), an anode (transparent conducting film), substrate (glass), n-type compact layer, absorber layer (Ag:CH3NH3Pbh and/or CH3NH3PM3), P3HT (p-type hole transport layer) and a cathode (silver) designed according to [35] as shown in Figure 1.
Figure 1 - CH3NH3Pbl3 device structure
It was modeled as shown in Figure 2. All the models were considered to be solid-state planar heterojunction p-i-n solar cells with low p-type-doped CH3NH3PbI3 sandwiched between the n-type ETM (compact TiO2) and p-type HTM (P3HT) layers according to [15].
Simulations were performed using light that propagated along z direction, through TiO2, CHsNHsPbIs and entering P3HT hole transporting layer in that order.
X
Figure 2 - CH3NH3PbI3 device structure
The same design was maintained for the one with or without the silver nanoparticle in its perovskite layer. The p-type hole transport (P3HT) layer also modelled as doped with ZnO, Cu2O and TiO2 nanoparticles separately and simulated using CST (microwave studio). Numerical simulation using SCAPS-1D simulation software was carried out to analysed the electrical parameters and the PCEs of the resulting solar cells. Table 1 and Table 2 shows the model parameter of the solar cells that were simulated.
Table 1 - Layer arrangement in CH3NH3PbI3 device structure
No DopantNPs Dopant on (HTM) Device layer structure
A1 P3HT ITO/TiO2/CH3NH3Pbh/P3HT/Ag
A2 ZnO P3HT:ZnO ITO/TiO2/CH3NH3Pbh/P3HT:ZnO/Ag
A3 CU2O P3HT:Cu2O ITO/TiO2/CH3NH3Pbh/P3HT:Cu2O/Ag
A4 T1O2 P3HT:TiO2 ITO/TiO2/CH3NH3Pbl3/P3HT:TiO2/Ag
Table 2 - Layer arrangement in CH3NH3PbI3 device structure
No Dopant NPs Dopant on (HTM) Device layer structure
B1 - P3HT ITO/TiO2/Ag:CHsNHsPbIs/P3HT/Ag
B2 ZnO P3HT:ZnO ITO/TiO2/Ag:CHNH3PbI3/P3HT:ZnO/Ag
B3 CU2O P3HT:CU2O ITO/TiO2/Ag:CHNH3PbI3/P3HT:Cu2O/Ag
B4 TiO2 P3HT:TiO2 ITO/TiO2/Ag:CHsNH3PbI3/P3HT:TiO2/Ag
Device Simulation. Two simulation software were used in this work. The SCAPS-1D simulation software was used to numerically simulate
photovoltaic cell analysis while other parameters were simulated using Computer Simulation Technology (CST) software. These are easy to use software's available from authorized vendors.
The solar cell models in Table 1 and Table 2 were simulated.
Choice of simulation parameters. The material optical parameters used in SCAPS-1D simulation were selectively picked from published articles by [35] and a number of supporting optoelectronic theories. The other optical constant and absorption coefficients for both CH3NH3PM3 and Ag:CH3NH3Pbl3 were obtained from [16]. A summary of some of these optical parameters are as tabulated in tables 1. It was adopted that the defect density of 1 x 1010 cm-3, electron hole and thermal velocity of 1.0 x107 cm/s, donor density, (ND) of zero (0), defect reference energy level was taken above Ev while energy level reference to 0.7e V respectively. Finally, energetic distribution and reference point for defect energy level (Et) were assumed to be single and above the highest Ev respectively when simulating the active layers (CH3NH3PM3, Ag:CH3NH3Pbl3) and perovskite/P3HT interface layers. Numerical simulation was finally performed.
Table 3 - Parameters for SCAPS-1D simulation
Parameters Unit Ag:CH3NH3Pbl3 CH3NH3PM3
Bandgap eV 1.662 1.711
Thickness nm 420 420
Dielectric 4.446 10
constant
Electron eV 4.20 4.11
affinity
Density of 1/cm3 1.0 x 10i8 2.25 x 1018
States (CB)
Density of States (VB) 1/cm3 1.0 x 10i8 1.0 x 1018
Electron cm2/Vs 1.6 2.20
mobility
Hole mobility cm2/Vs 1.6 2.20
Acceptor density, (Na) 1/cm3 3.2 x 1015 1.0 x 1018
Electron cross- cm2 1.0 x 10-16 1.0 x 10-13
section
Hole cross cm2 1.0 x 10-14 1.0 x 10-13
section area
Uniform total 1/cm3 4.5 x 10" 1.0 x 1012
(Nt)
Limitation on Simulations. All simulations were limited to either thickness, defect at hole transporting (HTM) layer, the density of states (DOS) and different nanoparticles on P3HT host HTM layer. As a result, thermal velocity of electrons and holes were taken as equal at 1 x 107 cm/s while an illumination of 1000W/m2, temperature of
25°C, and an air mass of 1.5G were adopted and the simulation software was limited to by SCAPS-1D simulation software to determine to short-circuit current density, Jsc, open-circuit voltage, Voc, fill factor, FF, and power conversion efficiency, n, for different doped HTM layer. All other simulations were subjected to CST (microwave studio) software.
RESULTS AND DISCUSSIONS
Influence of CH3NH3PN3 and Ag:CH3NH3Pbh layer thickness. Figure 3 shows the variation of thickness of CH3NH3PM3 and Ag:CH3NH3Pbl3 absorber layers with respect to open-circuit voltage.
Figure 3 - Ag:CH3NH3PbI3 perovskite solar cell model
It can be noted that the open-circuit voltage of CH3NH3PbI3 layer increases gradually as thickness increases to a certain peak point. This in effect implies that the efficiency increases up to a certain value which can be considered as the optimum at a specific thickness. Therefore, with increasing thickness, the short circuit current (Jsc) increases and therefore a thicker absorber layer will absorb more photons which in turn, will relatively create more electron-hole pairs resulting in higher open-circuit voltage values. From figure 3 also, it can be observed that a thickness of 320-440 nm is appropriate for Ag:CH3NH3Pbl3 perovskite layer for optimal photon absorption based on the AM 1.5G simulation radiation. The optimum thickness that recorded the highest VOC for both Ag:CH3NH3PbI3 and CH3NH3PbI3 layers was 420 nm. The gradual increase in Voc from 280-420 nm was attributed to the plasmonic contributions due to silver nanoparticles with a maximum localized surface plasmonic effect attained at 420 nm. Beyond this thickness, chances of recombination of electron-holes increase as
the charge carriers traverse the longer distance in thick films and therefore diffusion is hampered. Thickness is a major parameter that plays a vital role in the overall performance of the solar cell. It could be the thickness for the absorber layer, HTM layer or the back contact. However, the efficiency of a perovskite solar cell depends largely on its response to the solar spectrum as influenced by thickness.
-■-voc °f CH NH Pbl layer
voc °f CH NH Pbl layer
> 0.865
«
eg 0.860 0.855 •■s 0.850 .i 0.845
250 300 350 400 450 500
Thickness [nm]
ported by the experimental result by [16], who concluded that recombination expedites with increasing thickness.
Influence of Defect State at HTM / perovskite Interface Layer. Methyl ammonium lead triiodide films have a number of defects. These include point defects. A defect layer on the Ag:CHsNHsPbIs/ HTM interface layer was considered during simulations which took into account the interface recombinations. The simulation parameters used are shown in Table 4.
Table 4 - Parameters simulating perovskite / HTM
layer interface layer
Interface layer Unit Value/quantity
Capture cross section electrons cm2 1.0 x 10-18
Capture cross section holes cm2 1.0 x 10-16
Energy with respect to reference eV 0.050
Integrated total density 1/cm2 1.0 x 10+12
Figure 4 - Influence of thickness on open-circuit voltage perovskite layer
The thickness of Ag:CHsNHsPbIs absorber layer was varied from 280 nm to 500 nm while that of the HTM layer was varied between 28 nm to 50 nm. The simulated Voc was tabulated as shown in figure 1 using table s. Thin photovoltaic absorber layers are held responsible for less electron-hole recombination. In such cases, dark saturation current remains very low. This means that open-circuit voltage will remain relatively high. In cases where the thickness is increased, the dark saturation current also increases and as a result, open-circuit voltage decreases and in turn efficiency decreases. Normally, for ideal solar cells, the open-circuit voltage is obtained from (5):
(5)
where I0 and Il are dark saturation current and light-generated current, while kT/q and A are the thermal voltage and the photodiode ideality factor [31].
It also implies that the fill factor of this solar cell will decrease as thickness increase and the consequence will be that the cell internally consumes power reducing efficiency after a certain peak thickness. Similar observations were re-
Figure 5 shows the effect of interface defect density versus efficiency curves for three different nanoparticle dopants on the HTM layer. From figure 5, it can be noted that there was a negligible effect on efficiency above defect density of 1.12 x 1012 cm-3. When defect density went below 1.01 x 1012 cm-3, a notable decrease in PCEs was recorded.
14.0
13.5
13.0
12.5
12.0
11.5
^ 11.0
& 10.5 0
Ö 10.0 fc
9.5 9.0 8.5 8.0 7.5
LU
-■ — P3HT: Cu2O layer -•- P3HT: TiO2 layer -a- P3HT layer -T— P3HT: ZnO layer
Defect Density [cm - ]
Figure 5 - Defect density of Ag:CH3NH3PbI3/HTM interface layer versus efficiency
With an increase in defect density, the recombination rate increases and as a result efficiency decreases. It was noted that doping P3HT layers with binary impurities reduced its potential as a
0
2
4
6
8
10
12
4
6
8
HTM layers for hybrid perovskite solar cells. Such attempts have not been carried out through attempts to practically implemented this are on progress. HTM layer can be deposited by sputtering [10], copper oxidation [12, 15], spin coating, atomic layer deposition and even more expensive techniques like molecular beam epitaxial technique.
Influence of Density of State of perovskite Layer. Figure 6 shows the variation of density of state (DOS) with thickness.
250 300 350 400 450 500
Thickness [nm]
Figure 6 - Defect density of the perovskite layer versus thickness
voltage declines which leads to low electric conversion efficiency and hence poor solar cell performance.
Since low electron affinity of the HTM layer usually has a great significance on charge carrier mobility low affinity safeguards high-hole mobility. As a consequence, carrier mobility in P3HT as a hole transporting layer increases it as a reliable hole transport material (HTM) for hybrid perovskite heterojunction devices.
13 .5 -,
13.0
12.5
12.0
Ï. 11.5
o 110 -Q C Q_ O
-t" Ô 10.5 LU
I = 10.0
O 0 U O
9.5
ro
o
03 9.0 8.5
-■-P3HT HTM layer -•- P3HT:Cu2O HTM layer -i- P3HT:ZnO HTM layer -T- P3HT:TO HTM layer
Valance band effective density of state x 10 cm-
Figure 7 - Valance band effective density of state in CH3NH3PbI3 versus cell efficiency
CH NH Pbl layer
Ag:CH3NH3Pbl3 layer
14 -
13
2 -
Q 10
9 -
2
3
4
5
6
8 -
The effect of DOS of the CH3NH3PM3 perovskite absorber layer was simulated with respect to thickness without accounting on the influence of the doped HTM layers. It can be observed from figure 6 that the density of state (Nv) varied from 13.76 x 1019 cm-3 to 7.5 x 1019 cm-3 for CH3NH3PM3 layer and from 9.75 x 1019 cm-3 to 7.79 x 1019 cm-3 for Ag:CH3NH3Pbl3 layer. This suggested that as thickness increases, the rate of recombination increases and this introduces multiple parasitic capacitances that negative affect solar cell efficiency.
Influence of Valance band effective density of state on efficiency. Figure 7, 8 show the curves of valance band effective density of state versus efficiency for CH3NH3PM3 and Ag:CH3NH3Pbl3 layers. From the curves in figure 6, it can be noted that in general, the cell efficiency of CH3NH3PbI3 absorber layer decreases with the increase in valence band effective density (Nv). As the number of holes increases in the CH3NH3PbI3 absorber layer. Their possibility of taking part in reverse saturation current once the solar cell circuit is completed also increases. Consequently, the open-circuit
19 5 -
1 2 3 4 5 6
Valance band effective density of state x 1019 cm-3
Figure 8 - Valance band effective density of state in Ag:CH3NH3PbI3 versus cell efficiency
Influence of silver Back Contacts. Simulations were carried out using the silver metal paste as a prospective back contact for methyl ammonium lead triiodide perovskite solar cells to determine the effect of doping P3HT as its hole transport layer. Parameters used in simulating the back contact are as shown in Table 5 while Table 4 illustrates the simulation result of efficiency. It was ob-
- P3HT HTM layer P3HT:Cu2O HTM layer P3HT:ZnO HTM layer
P3HT:TiO HTM layer
served that the performance of the solar cells decreased depending on the type of nanoparticle material used. CU2O dopant had the highest efficiency while T1O2 dopant had the least efficiency. This showed that doped P3HT was energetically unfavourable for holes to travel towards the silver electrode with an opposing electric field within or close to HTM since the back contact becomes negative.
Table 5 - Parameters for simulating silver back contact
Parameters Unit Value/quantity
Surface recombination velocity of electrons cm/s 1.0x 10 +5
Surface recombination velocity of holes cm/s 1.0x 10 +7
Metal work function eV 4.736
Majority carrier barrier height relative to Ef eV 0.40
Majority carrier barrier height relative to Ev eV 0.3251
The decrease in efficiency was also attributed to the back contact as shown in Table 6.
Table 6 - Inf uence of (Ag) back contact
HTM Layer Thickness PCE (%) % PCE Decrease
P3HT 40 13.123 -
P3HT:ZnO 40 10.062 3.061
P3HT:Cu2O 40 12.184 2.939
P3HT:TiO2 40 9.091 4.032
When compared to Au contact used elsewhere [17, 18, 21, 28], it was anticipated that the lower work function of silver metal contact was attributed to the lower efficiency. It was recommended that Au should be given a priority when developing hybrid perovskite solar cells.
Numerical Analysis open-circuit voltage. Figure 4 shows a plot of the variation of open-circuit voltage curves for ZnO, Cu2O, and TiO2 nanoparticle dopants against P3HT HTM layer varied between 28-50 nm. For purposes of simulation, the thickness of HTM layer was varied between 28-50 nm at intervals of 2 nm. This thickness is the common thickness is used in many solar cells. The HTM layer containing ZnO, Cu2O, and TiO2 nanoparticle dopants in HTM layer were simulated to obtain open voltage currents. Their open-circuit voltages (Voc) were determined as well as their efficiencies. During a simulation,
theoretical constants used to estimate open-circuit voltages (Voc) included the fundamental parameters like bandgap, electron affinity, dielectric permittivity, electron, and hole mobility and how they can influence the HTM layers. The optimum open-circuit voltage obtained was as shown in Figure 4.
0.1890 0.1885 0.1880 > 0.1875 g 0.1870 >v 0.1865 0.1860 o 0.1855 t; 0.1850 g 0.1845
s= 0.1840
0)
O 0.1835 0.1830 0.1825 -
■■- P3HT HMT layer ■•- P3HT:Cu2O HMT layer P3HT:ZnO HMT layer T- P3HT:HO HMT layer
Thickness [nm]
Figure 9 - Influence of HTM thickness on open-circuit voltage
It was observed from Figure 9 that Cu2O had a very small significant contribution to the open-circuit voltage on P3HT layer as Voc values were relatively close to those of P3HT layer. This suggested that in the presence of P3HT layer, there is no need of introducing Cu2O nanoparticles. Its plasmonic contributions can be neglected. The presence of ZnO nanoparticles relatively reduced the contribution of P3HT layer to open-circuit voltages of the perovskite layer. The reduction was attributed to the higher recombination within the HTM layer as a result of plasmonic effects due to ZnO nanoparticles. Similarly, TiO2 registered the highest relative reduction of Voc as compared to all nanoparticles used. This suggested that its plasmonic contribution acted negatively in P3HT hole transport layer and should be neglected at all costs when developing a perovskite solar cell. These observations were attributed to the unique plasmonic properties of the plasmonic particles used.
Model Ag:CH3NH3PbI3 perovskite solar cell. For modelling and performing simulation using the SCAPS-1D simulator, structure by doping CH3NH3PM3 using silver nanoparticles and also by doping the P3HT hole transport material interfaced with a silver (Ag) metal back contact. Parameters for simulation were adopted from literature, experimental work and simulation using CST (microwave studio) software.
25
30
35
40
45
50
Table 7 - PC Efficiency of CH3NH3PW3 perovskite solar cell
HTM Layer Voc (V) Fill Factor PCE (%)
P3HT 0.889 69.4 13.123
P3HT:ZnO 0.881 57.6 10.062
P3HT:Cu2O 0.885 65.3 12.184
P3HT:TiO2 0.837 52.9 9.091
Figure 10 - Model device structure of Ag:CH3NH3PbI3 perovskite solar cell
Table 8 - PC Efficiency of Ag:CH3NH3Pbh perovskite solar cell
HTM Layer Voc (V) Fill Factor PCE (%)
P3HT 0.843 66.4 13.033
P3HT:ZnO 0.841 53.6 10.002
P3HT:Cu2O 0.842 60.3 12.114
P3HT:TiO2 0.836 48.9 9.071
The HTM layer structure suggested here is different from that proposed by other researches where Ag:CH3NH3Pbl3 absorber perovskite layer instead of CH3NH3PM3 absorber layer. In all model structures, CU2O, ZnO, and TIO2 were considered as dopant in HTM layer. It was concluded that Cu2O ensures the highest performance among dopant nanoparticles slightly lower than P3HT layer. This was attributed to the properties of Cu2O since it is a 2.17 eV direct bandgap p-type binary inorganic absorber solar cell material
[23]. Starting from P3HT layer through Cu2O, ZnO to TIO2 doped layers, the efficiency of 13.123 % and 9.071% FF range of 69.4% to 48.9 % for CH3NH3PM3 perovskite solar cell and 13.033 % and 9.091% FF range of 66.4% to 52.9 % CH3NH3PM3 perovskite solar cell.
CONCLUSION
As compared to other simulated perovskite solar cell efficiencies, the I-V characteristics obtained in this work reflect the performance outcome expected by this perovskite layer of 450 nm thickness exhibited by a valance band density of states of 3.2 x 1018 cm-3 and interface defect density of 1.12 x 1012 cm-3 respectively. ITO/ TO/ CH3NH3PbI3/P3HT/Ag perovskite structure gave the best performance among all the PSCs simulated. From the findings of this study, it was revealed that among all the simulated solar cells, the solar cell employing P3HT undoped HTM layer had the best performance. Open-circuit voltage and short circuit current changes were significant. This finding shows that we can modify the performance of a hybrid solar cell by modifying its organic HTM layer using binary inorganic plasmonic nanoparticles. It was therefore concluded that these findings can be used to justify the model in this paper as a potential alternative way to developing conventional hybrid perovskite solar cells. It was recommended that experimental investigation was required to determine its viability. It was concluded that binary inorganic nanoparticles hamper the performance of P3HT HTM layer for solar cell applications.
ACKNOWLEDGEMENT
The authors acknowledge the Department of Physics of Kenyatta University and Technical University of Mombasa.
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