The role of domain size and the weight ratio of fullerene and non-fullerene acceptors on performance of PM6:Y6: PCBM ternary solar cell.

doi:10.21203/rs.3.rs-1518516/v1

Recently, ternary solar cells have developed as a vital photovoltaic-technology since they combine the advantages of both single junction and tandem solar cells with their processing simplicity, mechanical flexibility, and lightweight. In this paper, we have investigated the role of domain size and the weight ratio of fullerene and non-fullerene acceptor on the performance of ternary blended PM6:Y6: PCBM organic solar cell. Using the effective medium approach and assuming the ternary blend of donor/acceptor1/acceptor2 nanocomposite as an effective integrated active layer, along with augmented Drift-diffusion formalism for the active layer of the organic solar cell, we have modeled the performance parameters of the device. The results show that the conversion efficiency of ternary solar cells depends on the distribution and size of both fullerene and non-fullerene acceptor domains. There are some optimal domain sizes where the optimum solar cell performance occurs. The obtained model results are in good agreement in comparison with experimental studies.

Ternary solar cells

non-fullerene acceptor

effective medium theory

power conversion efficiency

domain size

The primitive kind of organic solar cells (OSC) was the low-efficiency two-layer donor/acceptor (D/A) bulk heterojunction (BHJ) one, which later promoted into the mixed D/A phase BHJ structures. Among the BHJ solar cells, an outstanding choice is using fullerene derivatives as acceptors[1]. Since the emergence of blend polymer donor-fullerene acceptor structures, they developed rapidly, thus the structures with 11% power conversion efficiencies (PCE) were attained[2].

Polymer-fullerene structures, owing to their simple processing and fast development in the PCE, are an effective route to achieve a high PCE in OSCs. However, fullerene acceptors have some disadvantages making them less suitable for OSC devices[3], [4]. For example, fullerene derivatives have small band gaps and, therefore poor light harvesting ability[5], and also they are expensive to synthesize at high purity[6]. Fullerene acceptors also tend to aggregate in the solid photoactive layer, reducing device efficiency [7]. For the reasons stated, the research on BHJ D/A OSCs, now ever more addresses the development of non-fullerene acceptor materials which gradually overcome the insufficiencies of their fullerene counterparts[8]. Moreover, non- fullerene acceptor materials also have less energy dissipation, tunable absorption spectra, easy synthesis process and near infrared absorption[9], [10].

Conventional OSCs, are based on the bulk heterojunction with a binary component have the issue of absorption spectra mismatch of the two components with solar energy, which restricts the further improvement in PCE[11]. Accordingly, ternary OSCs have been well developed for overcoming such issues. In the ternary approach a third component, (as the donor or acceptor), is introduced into a binary blend to increase the absorption range of solar spectrum and improve the charge transport properties, leads to promotion of device’s performance parameters[12].

Some of the advantages of ternary systems compared to with binary OSCs are: (1) the third component can improve the photon absorption compared to absorption of binary system. (2) It can organize some extra charge transport pathways helps the carriers to transport more effectively. (3) The third component forms appropriate phase separation by intermolecular interactions thus it improves the morphology of active layers. (4) the fabrication process of ternary systems is simple due to the single active-layer fabrication conditions without the need for a multiple- stacked interfacial layer[13]–[15]. Moreover, all the performance enhancing approaches of BHJ solar cells, such as tuning the energy levels, adjusting the weight ratio of donors and acceptors, could be applied to improve the efficiency of the device[16].

In this study, the role of non-fullerene and fullerene acceptor domain’s size on performance parameters of high efficiency PM6:Y6: PCBM ternary OSC are investigated. In our studied structure, PBDB-TF (PM6) is high-performance photovoltaic material polymer, BTP-4F (Y6) is the wide bandgap non-fullerene acceptor and the [6, 6]-phenyl-C71-butyric acid methyl ester ( PC₇₀BM) acts as the fullerene acceptor.

The chemical structure and the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the donor and acceptor materials are shown in Fig. 1.a,b[12].

In the ternary solar cells with two acceptors, after light absorption by donor domains, excitons generated in the donor domain, dissociate into free electrons and holes at two pathways: the donor/acceptor1 (D/A1) and donor/acceptor2 (D/A2) interfaces[17]. The holes would transported through the donor channels to reach the anode and electrons would be transported to the cathode through the two parallel channels made by the two acceptors[18], [19].

In ternary systems, the role of domain size, distribution and morphology are very important problems, whereas with a certain weight ratio of donor and acceptors, several size distribution situations and multiple pathways could be applied. The essential issue is to satisfy the condition that the weight ratio and domain size lead to maximum light harvesting. In this work we have used a size-dependent effective medium theory to calculate an effective dielectric function for the ternary organic active layer. We have applied the modified Maxwell-Garnett theory which considers the non-uniform size dispersion of each component[20]. Here the donor polymer counts as host material and the acceptor1 and acceptor 2 count as guest components. In this method, we can calculate the absorption coefficient of the active layer for different values of weight ratio and size of acceptor domains which could help to design and fabrication of efficient ternary systems with optimum power conversion efficiencies. The effective medium theory (EMT) can replace the optical properties of a nanocomposite, with that of a homogeneous material provided that its dielectric polarization under light illumination would be the same as that of the nanocomposite[21]. Figure 2 shows schematically an overview of EMT. In the calculations, we have considered the domain size and filling fraction of the guest1 and guset2 are the variable parameters.

From the point of theoretical scheme, for modeling the active layer or the device, we have used the augmented drift- diffusion method considering the exciton dissociation rate, given by the Onsager-Braun model. Finally, considering the low and high volume fractions of the two acceptors, and also the small and large size of domain domains, the effect of different parameters of fullerene and non-fullerene acceptors embedded in the inorganic polymer host materials are investigated.

In a ternary structure, as the light absorbed inside the donor domains, an electrically neutral exciton is generated, which can randomly diffuse in several directions.

Once it reaches to the Donor/Acceptor1 (or Donor/Acceptor2) interfaces, the electron in the donor’s LUMO moves to acceptor1’s (or acceptor2’s) LUMO, which located at lower energy. [22]. On the other hand, since the light enters from the anode, most absorption occurs near the anode. therefore, excitons need to reach to the D/A interface before than they recombine, so that generate free charge carriers[23]. In a ternary system a lot of D/A interfaces exists which benefits the exciton dissociation process. The operative role of D/A interfaces is dependent on morphology parameters of acceptor domains such as size and distribution which therefore is imperative to be studied.

From the point of EMT, we have considered the active layer of the ternary blend solar cell, as a three-component nanocomposite material in which the PCBM polymer is the host and the PM6 fullerene and Y6 non-fullerene acceptors are the first and second hosts, respectively. In this method, considering the weight ratio and size of each guest, an effective dielectric function is calculated for the whole nanocomposite layer, which includes the optical and morphological properties of all three components.

One of the most applicable extensions of the well-known Maxwell-Garnett (MG) theory, is the Maxwell-Garnett-Mie (MGM) model, computes the effective dielectric function, by calculating the electric dipole polarizability of a composite from the Mie scattering theory. MGM theory, considers both extrinsic dynamic and intrinsic confinement effects as shown in Eq. 1[24]:

$\frac{{{\varepsilon _{eff}} - {\varepsilon _h}}}{{{\varepsilon _{eff}}+2{\varepsilon _h}}}=\frac{{3i{V_1}{\lambda ^3}}}{{16{\pi ^3}\bar {R}_{1}^{3}\varepsilon _{1}^{{3/2}}}}a_{{M1}}^{L}({\bar {R}_1})+\frac{{3i{V_2}{\lambda ^3}}}{{16{\pi ^3}\bar {R}_{2}^{3}\varepsilon _{2}^{{3/2}}}}a_{{M2}}^{L}({\bar {R}_2}){\text{ (1)}}$

Where${V_1}$, ${\bar {R}_1}$ and${V_2}$,${\bar {R}_2}$ are the volume fraction and mean radius of each type of guest components respectively and $\lambda$ is the wavelength. $a_{{M1}}^{1}({\bar {R}_1})$, $a_{{M1}}^{2}({\bar {R}_1})$ are the first electric Mie coefficient for first and second guest component calculated from Eq. 2.a, b:

\(\begin{gathered} a_{{M1}}^{1}({{\bar {R}}_1})=\frac{{\frac{{n_{{NP}}^{1}}}{{{n_h}}}{\psi _1}(\frac{{2\pi {n_h}}}{\lambda }{{\bar {R}}_1})\psi _{1}^{'}(\frac{{2\pi {n_h}}}{\lambda }{{\bar {R}}_1}) - {\psi _1}(\frac{{2\pi {n_h}}}{\lambda }{{\bar {R}}_1})\psi _{1}^{'}(\frac{{2\pi n_{{NP}}^{1}}}{\lambda }{{\bar {R}}_1})}}{{\frac{{n_{{NP}}^{1}}}{{{n_h}}}{\psi _1}(\frac{{2\pi {n_h}}}{\lambda }{{\bar {R}}_1})\xi _{1}^{'}(\frac{{2\pi {n_h}}}{\lambda }{{\bar {R}}_1}) - {\xi _1}(\frac{{2\pi {n_h}}}{\lambda }{{\bar {R}}_1})\psi _{1}^{'}(\frac{{2\pi n_{{NP}}^{1}}}{\lambda }{{\bar {R}}_1})}}{\text{ (2}}{\text{.a)}} \hfill \\ a_{{M1}}^{2}({{\bar {R}}_1})=\frac{{\frac{{n_{{NP}}^{1}}}{{{n_h}}}{\psi _1}(\frac{{2\pi {n_h}}}{\lambda }{{\bar {R}}_2})\psi _{1}^{'}(\frac{{2\pi {n_h}}}{\lambda }{{\bar {R}}_2}) - {\psi _1}(\frac{{2\pi {n_h}}}{\lambda }{{\bar {R}}_2})\psi _{1}^{'}(\frac{{2\pi n_{{NP}}^{1}}}{\lambda }{{\bar {R}}_2})}}{{\frac{{n_{{NP}}^{1}}}{{{n_h}}}{\psi _1}(\frac{{2\pi {n_h}}}{\lambda }{{\bar {R}}_2})\xi _{1}^{'}(\frac{{2\pi {n_h}}}{\lambda }{{\bar {R}}_2}) - {\xi _1}(\frac{{2\pi {n_h}}}{\lambda }{{\bar {R}}_2})\psi _{1}^{'}(\frac{{2\pi n_{{NP}}^{1}}}{\lambda }{{\bar {R}}_2})}}{\text{ (2}}{\text{.b)}} \hfill \\ \end{gathered}\)

Where ${\psi _1},{\xi _1},\psi _{1}^{'},\xi _{1}^{'}$ are the first-order Riccati-Bessel functions and their derivations respectively.

Using effective medium approach and assuming the blend of Donor/Acceptor1/Acceptor2 nanocomposite as an effective united active layer of the organic solar cell, we use the Koster’s augmented Drift-diffusion, formalism for the active layer of OSC. Using the uniform electric field approximation which is applicable for sufficiently thin active layer thickness, the electrostatic field is simply could be written as in Eq. 3[25].

$E=\frac{{{V_{app}}+\Delta {\Phi _2} - \Delta {\Phi _1}}}{L}{\text{ (3)}}$

Where is the active layer thickness, $\Delta {\Phi _1}$and$\Delta {\Phi _2}$are respectively the work-function difference between the front and bottom electrode and the active layer. ${V_{app}}$ is the applied voltage between anode and cathode. Figure 2 demonstrates a schematic view of the studied ternary blend organic solar cell.

Following Koster and co-worker’s, augmented drift- diffusion formalism, the steady-state continuity equation for holes can be written as Eq. 4[26].

$- {V_{th}}{\mu _p}\frac{{{d^2}p}}{{d{x^2}}}+E{\mu _p}\frac{{dp}}{{dx}}=P(E){G_{opt}} - (1 - P(E))R{\text{ (4)}}$

Where ${V_{th}}={\raise0.7ex\hbox{${KT}$} \!\mathord{\left/ {\vphantom {{KT} q}}\right.\kern-0pt}\!\lower0.7ex\hbox{$q$}}$ is the thermal voltage, ${\mu _p}$is the mobility of holes, ${G_{opt}}$ is the optical carrier generation rate and $P(E)$is the exciton’s dissociation probability, calculated according to the Onsager-Braun theory, presented in Eq. 5a-c.

$\begin{gathered} P(T,E,{k_f},a)=\frac{{{k_d}}}{{{k_d}+{k_f}}}{\text{ (5}}{\text{.a)}} \hfill \\ {k_d}(T,E,a)=\frac{{3\mu e}}{{4\pi \varepsilon {a^3}}}{e^{ - [\Delta \varepsilon (a)/KT]}}\frac{{8\pi \varepsilon {\varepsilon _0}{K^2}{T^2} \times {J_1}[2\sqrt { - 2b(T,E)} ]}}{{ - 2{e^3}E}}{\text{ (5}}{\text{.b)}} \hfill \\ \Delta \varepsilon (a)=\frac{{{e^2}}}{{4\pi \varepsilon {\varepsilon _0}a}}{\text{ (5}}{\text{.c)}} \hfill \\ \end{gathered}$

In Eq. 5.b. the mobility total mobility of electrons and holes $\mu ={\mu _p}+{\mu _n}$, ${J_1}$ is the Bessel function of the first kind of order of 1, is the initial pair separation distance of the charge transfer exciton, and $\Delta \varepsilon (a)$ is the pair binding energy. The bimolecular (or Langevin’s) recombination rate ${\text{R}}$is given by Eq. 6[27].

${\text{R=}}\frac{{{\text{q}}\mu (np - n_{i}^{2}){\text{ }}}}{{2\varepsilon }}{\text{ (6)}}$

Where${{\text{n}}_i}$is the intrinsic carrier density of electrons and holes. Finally after solving the continuity equation with applying the boundary conditions, the complete answer to the Eq. 4 could be written as presented in Eq. 7[28].

$\begin{gathered} {\text{p(x)=[}}{N_V}\exp (\frac{{ - {\varphi _2}}}{{q{V_t}}}) - \frac{{{N_V}\exp (\frac{{{E_g}+{\varphi _1}}}{{{\varphi _2}}}) - \frac{{PGL}}{{E{\mu _p}}}}}{{\exp (\frac{{qEL}}{{KT}}) - 1}}]+ \hfill \\ {\text{ + }}[\frac{{{N_V}\exp (\frac{{{E_g}+{\varphi _1}}}{{{\varphi _2}}}) - \frac{{PGL}}{{E{\mu _p}}}}}{{\exp (\frac{{qEL}}{{KT}}) - 1}}{\text{ }}\exp (\frac{{qEx}}{{KT}})]+\frac{{PGx}}{{E{\mu _p}}}{\text{ (7)}} \hfill \\ \end{gathered}$

Where ${N_V}$is the effective density of states in the valence band. The steady-state continuity equation of electrons could be written in a similar method. Applying an analogous calculation for the electrons, the total current density, which is the sum of the drift and diffusion current density of electron and holes, obtains.

In order to take into account the effect of each component’s optical parameters, we calculated the absorption coefficient of each of them and also the total effective absorption coefficient of active layer via dielectric function of each component and the calculated effective dielectric function respectively. The absorption coefficient in this method could be defines as Eq. 8.

$\alpha (\lambda )=\frac{{4\pi }}{\lambda }{\left\{ { - \operatorname{Re} ({\varepsilon _{eff}})+\frac{1}{2}\left[ {\operatorname{Re} (\varepsilon _{{_{{eff}}}}^{2})+\operatorname{Im} (\varepsilon _{{_{{eff}}}}^{2})} \right]} \right\}^{\frac{1}{2}}}{\text{ (8)}}$

In table.1 we have presented the experimental values that we have used for mobility of electron and hole of PM6:Y6: PCBM with different values of Y6 percent.

Table 1

electron and hole mobility for different values of Y6 percent[29].
Y6 (%)	${\mu _n}({\raise0.7ex\hbox{${{m^2}}$} \!\mathord{\left/ {\vphantom {{{m^2}} {V.s}}}\right.\kern-0pt}\!\lower0.7ex\hbox{${V.s}$}})$	${\mu _p}({\raise0.7ex\hbox{${{m^2}}$} \!\mathord{\left/ {\vphantom {{{m^2}} {V.s}}}\right.\kern-0pt}\!\lower0.7ex\hbox{${V.s}$}})$
10	$4.2 \times {10^{ - 14}}$	$2.02 \times {10^{ - 8}}$
20	$1.42 \times {10^{ - 12}}$	$1.82 \times {10^{ - 8}}$
30	$8.01 \times {10^{ - 9}}$	$1.5 \times {10^{ - 8}}$
40	$2.1 \times {10^{ - 9}}$	$2.82 \times {10^{ - 8}}$
50	$2.82 \times {10^{ - 8}}$	$2.82 \times {10^{ - 8}}$
60	$2.09 \times {10^{ - 8}}$	$2.82 \times {10^{ - 8}}$
70	$2.09 \times {10^{ - 8}}$	$1.41 \times {10^{ - 8}}$

At the next step, we investigated the effects of changes in the percentage of non-fullerene acceptor on the quantum efficiency of the studied structure.

$\Delta EQ{E_x}=\frac{{EQ{E_x} - EQ{E_0}}}{{EQ{E_0}}}{\text{ (9)}}$

Where is the percent of Y6 as non-fullerene acceptor and $EQ{E_0}$is the external quantum efficiency of the system of binary PM6: PCBM blend.

In order to consider the physical constraint due to the size of the domains by weight percentage, we considered a slab with dimensions of $100 \times 100 \times 100$nm³ and calculated the distribution of domains with maximum average dimensions of PCBM acceptor with a fixed weight ratio for Y6 acceptor at 0.5.

Fig.3 shows the Real and imaginary parts of dielectric function of PM6 as donor polymer, Y6 as non-fullerene acceptor and PC₇₀BM as fullerene acceptor.

Using the real and imaginary parts of the dielectric function and the Eq. (8), the absorption coefficient of each of the components can be obtained. Figure 4 shows the normalized absorption of each component of ternary active layer. We have calculated the absorption coefficient of PM6 as donor polymer, Y6 as non-fullerene acceptor and PC70BM as fullerene acceptor using the real and imaginary parts of dielectric function presented in Fig. 3.

In order to compare the binary configuration morphology and the ternary configuration with different weight percentages and domain sizes, we first calculated the characteristics of the binary solar cell. Figure 5 shows the characteristic parameters of PM6:Y6 binary solar cell versus the size of Y6 acceptor domains. We have presented the variation of fill factor (FF), short current density (Jsc) and power conversion efficiency ($\eta$) while the open circuit voltage (${V_{OC}}$) shows a constant behavior with the value of 0.8 volt.

It can be argued that when the light enters the binary system, along with absorbing light and producing excitons in the donor regions, the excitons diffuses inside the donor and reach the donor-acceptor interfaces. The larger the size of the acceptor domains, the easier it is for excitons to reach the interfaces and dissociate. Then the electrons begin to move in the acceptor domains on the way to reach to the contacts. On the other hand, if the size of the acceptor domains is larger than a certain amount, the probability of recombination of electrons inside the acceptor also increases, which leads to a decrease in current and ultimately the efficiency of the solar cell.

At a next step, in a ternary system, we investigate the role of domain size changes in the both fullerene and non-fullerene domains. Figure 6 shows the results for 5 different weight ratios.

Table 2

Electron and hole mobility of PM6:Y6: PCBM for different values of PCBM percent[30]
weight ratio	${\mu _n}({\raise0.7ex\hbox{${{m^2}}$} \!\mathord{\left/ {\vphantom {{{m^2}} {V.s}}}\right.\kern-0pt}\!\lower0.7ex\hbox{${V.s}$}})$	${\mu _p}({\raise0.7ex\hbox{${{m^2}}$} \!\mathord{\left/ {\vphantom {{{m^2}} {V.s}}}\right.\kern-0pt}\!\lower0.7ex\hbox{${V.s}$}})$
0.5:0.5:0	$1.3 \times {10^{ - 8}}$	$2.4 \times {10^{ - 8}}$
0.4:0.5:0.1	$2.02 \times {10^{ - 8}}$	$2.64 \times {10^{ - 8}}$
0.3:0.5:0.2	$2.82 \times {10^{ - 8}}$	$2.82 \times {10^{ - 8}}$
0.2:0.5:0.3	$3.66 \times {10^{ - 8}}$	$2.89 \times {10^{ - 8}}$
0.1:0.5:0.4	$4.05 \times {10^{ - 8}}$	$2.82 \times {10^{ - 8}}$

From the Fig. 6a-e it can be comprehend that in each case, with increasing the size of fullerene and non-fullerene acceptors, initially an increase and then a relative decrease is identified. It can be inferred that when the size of the acceptors is very small, they are more numerous islands, which leads to more interface areas, and as a result, the excitons have more chance to be dissociated. But it is also possible that the excited excitons will decay afterward.

As the size of the acceptors increases, the number of interfaces decreases, but on the other hand, the size of the acceptor domains increases and the excitons that reach the interface, could separate more efficiently, which leads to increases the system efficiency. But after a while, as the size of the acceptor domains increases (by the same weight percentage), the number of exponent domains more decreases, which gradually becomes as a bulk heterojunction system, and so due to the very small amount of interfaces, the exciton dissociation is so insufficient, which reduces the current density and hence the efficiency of the solar cell. Among the studied percentages, the percentage of fullerene acceptor of 0.3 shows the highest value in most domain sizes. As a result, there is a certain amount between the donor and acceptor percentages that achieves the highest conversion efficiency of the solar cell. That is, there must be a balance between the amount of donor and the acceptor that both the absorption and production and separation of excitons can be done effectively.

In order to investigate the role of Y6 non-fullerene acceptor on performance of organic solar cell, we have applied the Y6 dependent mobility values of electron and hole from an experimental work has been done for a binary PM6:Y6 system, In this way, we have considered the relative changes of mobility in a binary system and using the exact experimental value of mobility for one percent of ternary system, we have fitted the other values using the relative change behavior of the similar binary system. Using this method we have calculated the values of electron and hole mobility in ternary blend with different values of non-fullerene acceptor as presented in Fig. 7.

As can be seen from Fig. 8, with the increase in the percentage of non-fullerene acceptor, initially at low percent (~ 10%) compared to the binary state, a decrease in the visible areas is observed. After that, with increasing percentage of Y6, an increasing in quantum efficiency in visible range can be seen. Finally, considering the whole spectrum studied, the maximum amount of increasing quantum efficiency in total is related to 50% of Y6. Table.3 shows the total increment in quantum efficiency with different percent of Y6 non-fullerene acceptor.

Table 3

Relative enhancement in EQE with different percent of Y6 non-fullerene acceptor.
Y6 (%)	$\int\limits_{{300}}^{{1000}} {\Delta (EQE).d\lambda }$
10	-6.06
20	-4.54
30	1.43
40	2.15
50	2.21
60	1.82
70	1.14

It can be seen from the table that in the case of 50% non-fullerene acceptor, the enhancement ratio is maximum. Also considering the experimental mobility values of table.1 the mobility of electron and hole in the case of 50% non-fullerene acceptor, are identical which related to balanced charge transport process leads to maximum enhancement of external quantum efficiency[31]. Figure 9 represents the relative difference of characteristic performance parameters of PM6:Y6: PCBM ternary blend solar cell with different percent of Y6 non-fullerene acceptor.

blend solar cell with different percent of Y6 non-fullerene acceptor.

As can be realized from Fig. 9, V_oc values in all cases show a relatively constant behavior. However, the J_sc and the FF, and consequently the conversion efficiency of different percentages, show relative changes with the value of Y6 non-fullerene acceptor percent, which reaches the maximum possible value in the amount of 50%. Figure 10 shows the J-

V curve of the studied ternary blend organic solar cell and a comparison with previous experimental works[12]. The weight ratio of ternary blend in the experimental paper is 0.42:0.5:0.083.

We have studied the role of domain size and weight ratio of PCBM fullerene and Y6 non-fullerene acceptors on performance of ternary blended PM6:Y6: PCBM organic solar cell. Using the size-dependent effective medium approach, we have assumed the blend of donor/acceptor1/acceptor2 nanocomposite as an integrated effective active layer of the organic solar cell. We have used the Koster’s augmented Drift-diffusion, formalism for modeling the active layer of OSC. The results show that the conversion efficiency of ternary solar cells depends on the weight ratio and domain size of the both fullerene and non-fullerene acceptors. Based on the results, there are optimal domain size and weight ratio in which the best solar cell performance occurs. The model results are also compared with previous experimental results and shows a satisfactory agreement.

Acknowledgment

This work was supported by Iran National Science Foundation (INSF) No. 96015716.

Declarations

There is no conflict of interest to declare.

R. S. Gurney, D. G. Lidzey, and T. Wang, “A review of non-fullerene polymer solar cells: From device physics to morphology control,” Reports Prog. Phys., vol. 82, no. 3, 2019.
J. Zhao et al., “Efficient organic solar cells processed from hydrocarbon solvents,” Nat. Energy, vol. 1, no. 2, 2016.
Y. Chang et al., “14%-efficiency fullerene-free ternary solar cell enabled by designing a short side-chain substituted small-molecule acceptor,” Nano Energy, vol. 64, p. 103934, Oct. 2019.
L. Ma et al., “A ternary organic solar cell with 300 nm thick active layer shows over 14% efficiency,” Sci. China Chem., vol. 63, no. 1, pp. 21–27, 2020.
P. Schilinsky, C. Waldauf, and C. J. Brabec, “Recombination and loss analysis in polythiophene based bulk heterojunction photodetectors,” Appl. Phys. Lett., vol. 81, no. 20, pp. 3885–3887, 2002.
J. T. Bloking et al., “Comparing the device physics and morphology of polymer solar cells employing fullerenes and non-fullerene acceptors,” Adv. Energy Mater., vol. 4, no. 12, pp. 1–12, 2014.
T. Wang, A. J. Pearson, D. G. Lidzey, and R. A. L. Jones, “Evolution of structure, optoelectronic properties, and device performance of polythiophene:fullerene solar cells during thermal annealing,” Adv. Funct. Mater., vol. 21, no. 8, pp. 1383–1390, 2011.
L. Guguloth, P. V. Raja Shekar, V. S. Reddy Channu, and K. Kumari, “Effect of reduced fluorinated graphene oxide as ternary component on synergistically boosting the performance of polymer bulk heterojunction solar cells,” Sol. Energy, vol. 225, no. June, pp. 259–265, 2021.
Z. Jia et al., “High performance tandem organic solar cells via a strongly infrared-absorbing narrow bandgap acceptor,” Nat. Commun., vol. 12, no. 1, pp. 1–10, 2021.
W. Huang, P. Cheng, Y. M. Yang, G. Li, and Y. Yang, “High-Performance Organic Bulk-Heterojunction Solar Cells Based on Multiple-Donor or Multiple-Acceptor Components,” Adv. Mater., vol. 30, no. 8, pp. 1–24, 2018.
Y. Chang et al., “Achieving Efficient Ternary Organic Solar Cells Using Structurally Similar Non-Fullerene Acceptors with Varying Flanking Side Chains,” Adv. Energy Mater., vol. 11, no. 14, pp. 1–9, 2021.
M. A. Pan et al., “16.7%-efficiency ternary blended organic photovoltaic cells with PCBM as the acceptor additive to increase the open-circuit voltage and phase purity,” J. Mater. Chem. A, vol. 7, no. 36, pp. 20713–20722, 2019.
N. Gasparini, A. Salleo, I. McCulloch, and D. Baran, “The role of the third component in ternary organic solar cells,” Nat. Rev. Mater., vol. 4, no. 4, pp. 229–242, 2019.
F. Liu et al., “Organic Solar Cells with 18% Efficiency Enabled by an Alloy Acceptor: A Two-in-One Strategy,” Adv. Mater., vol. 33, no. 27, pp. 1–8, 2021.
J. Wang et al., “Ternary Nonfullerene Polymer Solar Cells with a Power Conversion Efficiency of 11.6% by Inheriting the Advantages of Binary Cells,” ACS Energy Lett., vol. 3, no. 3, pp. 555–561, 2018.
X. Wang et al., “Ternary Organic Photovoltaic Cells Exhibiting 17.59% Efficiency with Two Compatible Y6 Derivations as Acceptor,” Sol. RRL, vol. 5, no. 3, pp. 1–9, 2021.
K. Weng et al., “Ternary organic solar cells based on two compatible PDI-based acceptors with an enhanced power conversion efficiency,” J. Mater. Chem. A, vol. 7, no. 8, pp. 3552–3557, 2019.
T. Ameri, P. Khoram, J. Min, and C. J. Brabec, “Organic ternary solar cells: A review,” Adv. Mater., vol. 25, no. 31, pp. 4245–4266, 2013.
Q. An, F. Zhang, J. Zhang, W. Tang, Z. Deng, and B. Hu, “Versatile ternary organic solar cells: A critical review,” Energy Environ. Sci., vol. 9, no. 2, pp. 281–322, 2016.
V. Khiratkar, R. Aepuru, and H. S. Panda, “Morphology-controlled ultrafine BaTiO3-based PVDF-HFP nanocomposite: Synergistic effect on dielectric and electro-mechanical properties,” Bull. Mater. Sci., vol. 41, no. 4, pp. 1–9, 2018.
Z. Arefinia, “Analytical Modeling Based on Modified Effective Medium Theories for Optical Properties of Photovoltaic Material-Incorporated Plasmonic Nanoparticles,” Plasmonics, vol. 15, no. 6, pp. 1661–1673, Dec. 2020.
D. D. Y. Setsoafia, K. S. Ram, H. M. Rad, D. Ompong, N. K. Elumalai, and J. Singh, “Optimizing Device Structure of PTB7-Th:PNDI-T10 Bulk Heterojunction Polymer Solar Cells by Enhancing Optical Absorption,” Energies, vol. 15, no. 3, 2022.
M. Rita Narayan and J. Singh, “Study of the mechanism and rate of exciton dissociation at the donor-acceptor interface in bulk-heterojunction organic solar cells,” J. Appl. Phys., vol. 114, no. 7, 2013.
I. Y. Yaremchuk, “Optical properties of nanocomposite materials based on plasmon nanoparticles,” Semicond. Phys. Quantum Electron. Optoelectron., vol. 21, no. 2, pp. 195–199, 2018.
M. M. Mandoc, L. J. Koster, and P. W. Blom, “Optimum charge carrier mobility in organic solar cells,” Appl. Phys. Lett., vol. 133504, no. 2007, pp. 8–11, 2012.
L. J. A. Koster, E. C. P. Smits, V. D. Mihailetchi, and P. W. M. Blom, “Device model for the operation of polymer / fullerene bulk heterojunction solar cells,” Phys. Rev. B 72, vol. 72, no. August, pp. 1–9, 2005.
S. Nazerdeylami, “Dominant recombination mechanism in perovskite solar cells: A theoretical study,” Sol. Energy, vol. 206, no. March, pp. 27–34, 2020.
S. M. A. and M. Z. K. Mesbahus Saleheen, “Analytical Model for Voltage-Dependent Photo and Dark Currents in Bulk Heterojunction,” energies, vol. 9, no. 412, pp. 1–14, 2016.
N. Yao et al., “Efficient Charge Transport Enables High Efficiency in Dilute Donor Organic Solar Cells,” J. Phys. Chem. Lett., vol. 12, no. 20, pp. 5039–5044, 2021.
Y. Jiang and X. Zhu, “High-Performance Ternary Organic Solar Cells Enabled by Synergizing Fullerene and Non-fullerene Acceptors,” Org. Mater., vol. 03, no. 02, pp. 254–276, 2021.
D. Li et al., “Enhanced and Balanced Charge Transport Boosting Ternary Solar Cells Over 17% Efficiency,” Adv. Mater., vol. 32, no. 34, 2020.

Y6 (%)	\({\mu _n}({\raise0.7ex\hbox{${{m^2}}$} \!\mathord{\left/ {\vphantom {{{m^2}} {V.s}}}\right.\kern-0pt}\!\lower0.7ex\hbox{${V.s}$}})\)	\({\mu _p}({\raise0.7ex\hbox{${{m^2}}$} \!\mathord{\left/ {\vphantom {{{m^2}} {V.s}}}\right.\kern-0pt}\!\lower0.7ex\hbox{${V.s}$}})\)
10	\(4.2 \times {10^{ - 14}}\)	\(2.02 \times {10^{ - 8}}\)
20	\(1.42 \times {10^{ - 12}}\)	\(1.82 \times {10^{ - 8}}\)
30	\(8.01 \times {10^{ - 9}}\)	\(1.5 \times {10^{ - 8}}\)
40	\(2.1 \times {10^{ - 9}}\)	\(2.82 \times {10^{ - 8}}\)
50	\(2.82 \times {10^{ - 8}}\)	\(2.82 \times {10^{ - 8}}\)
60	\(2.09 \times {10^{ - 8}}\)	\(2.82 \times {10^{ - 8}}\)
70	\(2.09 \times {10^{ - 8}}\)	\(1.41 \times {10^{ - 8}}\)

weight ratio	\({\mu _n}({\raise0.7ex\hbox{${{m^2}}$} \!\mathord{\left/ {\vphantom {{{m^2}} {V.s}}}\right.\kern-0pt}\!\lower0.7ex\hbox{${V.s}$}})\)	\({\mu _p}({\raise0.7ex\hbox{${{m^2}}$} \!\mathord{\left/ {\vphantom {{{m^2}} {V.s}}}\right.\kern-0pt}\!\lower0.7ex\hbox{${V.s}$}})\)
0.5:0.5:0	\(1.3 \times {10^{ - 8}}\)	\(2.4 \times {10^{ - 8}}\)
0.4:0.5:0.1	\(2.02 \times {10^{ - 8}}\)	\(2.64 \times {10^{ - 8}}\)
0.3:0.5:0.2	\(2.82 \times {10^{ - 8}}\)	\(2.82 \times {10^{ - 8}}\)
0.2:0.5:0.3	\(3.66 \times {10^{ - 8}}\)	\(2.89 \times {10^{ - 8}}\)
0.1:0.5:0.4	\(4.05 \times {10^{ - 8}}\)	\(2.82 \times {10^{ - 8}}\)

The role of domain size and the weight ratio of fullerene and non-fullerene acceptors on performance of PM6:Y6: PCBM ternary solar cell.

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Abstract

Figures

Introduction

Modeling

Results And Discussion

Conclusion

Declarations

Acknowledgment

Declarations

References

Status:

Journal Publication

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