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Motivated by recent study on synthesized N, N-diphenylaniline (DPA)-based dyes [DOI: https://doi.org/10.1016/j.solener.2022.01.062 ] for use in dye-sensitized solar cells (DSSCs), we theoretically design several dyes and explore their potential for enhancing the efficiency of DSSCs. Our designed dyes are based on the molecular structure of synthesized DPA-azo-A and DPA-azo-N dyes with a donor-π-bridge-acceptor (D-π-A) framework. In this research, we aim to develop the power conversion efficiency (PCE) of DSSCs by fine-tuning the molecular structure of the synthesized dyes. To this end, we focus on designing dyes by replacing the units of DPA-azo-A and DPA-azo-N with a variety of donor, π-bridge, and acceptor. Hence the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations are done to explore their structure, electronic, optical, charge transport, and photovoltaic properties. Among all newly designed and reference dyes, the D3-azo-N and DPA-π3-N dyes which are designed by substituting the donor (DPA) and π-bridge (azo) units of DPA-azo-N with D3 and π3, respectively exhibit the highest PCE of 45.46% (for D3-azo-N) and 43.20% (for DPA-π3-N) and can be favorable dyes for improving the efficiency of DSSCs. Therefore, the dyes that are designed by substituting the donor and π-bridge units of synthesized dyes have more impact on improving the efficiency of DSSCs than those that involve replacing the acceptor units. Consequently, our theoretical findings will provide valuable insights for the experimentalists to employ these novel effective dyes and boost the performance of DSSCs.
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Non-radiative recombination of perovskite solar cells (PSCs) will increase as a result of the numerous crystallographic defects that the solution-grown perovskite films will cause, particularly at the grain boundary and film surface. As a result, it negatively influences the performance of the device. Consequently, lowering perovskite film defects is a useful strategy for raising the efficiency of PSCs. This study reports a grain regeneration and passivation approach that can decrease the recombination loss of the perovskite layer/charge transfer layer interface and the grain border. Guanidine iodide (GAI) treatment of perovskite films is the means by which this objective is accomplished. Unlike most methods that use GAI to post-treatment the perovskite layer or add GAI into the perovskite precursor solution, this work uses GAI for pre-treatment before spin coating the perovskite layer. It can effectively passivate surface defects and increase the grain size of perovskite films by controlling the crystallization process. The water stability of devices was enhanced, the short-circuit current (Jsc), filling factor (FF), and power conversion efficiency (PCE) of PSCs were markedly improved, and non-radiative recombination was successfully reduced. The best efficiency of PSCs was 20.56% after the additional GAI treatment was applied to the perovskite layer, an 11.9% increase over the efficiency of the control device without GAI treatment. This method has the advantage of being simple and straightforward, providing a feasible pathway for the low-cost preparation and commercialization of PSCs.
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Here in, we have designed two new unfused non-fullerene small molecules based on asymmetric benzo[1,2-b:3.4-b', 6,5-b"]trithiophene (BTT) central donor core and different terminal units, i.e. 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (NFA-4) and 1,3-diethyl-2-thioxodi hydropyrimidine-4,6(1H,5H)-dione (NFA-5) and their optical and electrochemical properties were investigated. Employing a wide band-gap copolymer D18, the binary D18: NFA-4 and D18:NFA-5 bulk heterojunction-based organic solar cells realized an overall power conversion efficiency of about 17.07% and 11.27 %, respectively. The higher value of power conversion efficiency for the NFA-4-based organic solar cells, as compared to the NFA-5 counterpart, is attributed to the enhanced values of short circuit current, open circuit voltage, and fill factor. After the incorporation of NFA-5 into the binary bulk heterojunction D18:NFA-4, the ternary organic solar cells attained a power conversion efficiency of 18.05 %, which is higher than that for the binary counterparts and attributed to the increased values of short circuit current, fill factor, and open circuit voltage. The increased value of short circuit current is associated with the effective utilization of excitons through the energy transfer from the NFA-5 to NFA-4 as the NFA-4 exhibits a more significant dipole moment than the NFA-5 and is effectively dissociated into a free charge carrier.
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Solid additives have drawn great attention due to their numerous appealing benefits in enhancing the power conversion efficiencies (PCEs) of organic solar cells (OSCs). To date, various strategies have been reported for the selection or design of non-volatile solid additives. However, the lack of a general design/evaluation principles for developing non-volatile solid additives often results in individual solid additives offering only one or two efficiency-boosting attributes. In this work, we propose an integrated omnidirectional strategy for designing non-volatile solid additives. By validating the method on the 4,5,9,10-pyrene diimide (PyDI) system, a novel non-volatile solid additive named PyMC5 was designed. PyMC5 is capable of enhancing device performance by establishing synergistic dual charge transfer channels, forming appropriate interactions with active layer materials, reducing non-radiative voltage loss and optimizing film morphology. Notably, the binary device (PM6:L8-BO) treated by PyMC5 achieved a PCE over 19.5%, ranking among the highest reported to date. In addition, the integration of PyMC5 mitigated the degradation process of the devices under photo- and thermal-stress conditions. This work demonstrates an efficient integrated omnidirectional approach for designing non-volatile solid additives, offering a promising avenue for further advancements in OSC development.
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Developing organic solar cells (OSCs) processable with halogen-free, non-aromatic solvents is crucial for practical applications, yet challenging due to the limited solubility of most photoactive materials. This study introduces high-performance terpolymers processable in tetrahydrofuran (THF) by incorporating dithienophthalimide (DPI) into the PM6 backbone. DPI extends the absorption band, lowers HOMO levels, and improves THF solubility and film crystallinity through its large dipole moment effect. Optimal PBD-10:L8-BO devices processed with THF achieved a competitive power conversion efficiency (PCE) of 18.79%, approaching chloroform-processed devices (19.04%). By introducing PBTz-F as a second donor, ternary OSCs reached an impressive 19.45% PCE when processed with THF. This improvement stems from enhanced photon generation, improved morphology, better charge transport, longer exciton lifetimes, efficient charge dissociation and collection, and suppressed recombination. These PCEs of 18.79% and 19.45% for binary and ternary blend OSCs, respectively, represent the highest reported efficiencies for OSCs processed with halogen-free, non-aromatic solvents. This work demonstrates significant progress in eco-friendly OSC fabrication, paving the way for more sustainable and commercially viable organic photovoltaic technologies.
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This study presents a significant advancement in tandem dye-sensitized solar cells (T-DSSCs) through the strategic synthesis of novel triazatruxene (TAT) sensitizers MS-1 and MS-2. These organic sensitizers demonstrate exceptional light-harvesting capacity and overall performance, pushing the boundaries of power conversion efficiency (PCE) in DSSCs. The MS-1-based DSSCs achieved an impressive PCE of 12.81%, while MS-2 sensitizers reached a notable 10.92%. These efficiencies represent significant improvements over the conventional N719 dye (7.60%), demonstrating the potential of metal-free organic sensitizers in DSSC technology. The key to these noteworthy results lies in the molecular design of the organic sensitizers. The triazatruxene donor segment in the MS-1 and MS-2 dyes, featuring a rigid structure and efficient intramolecular charge transfer (ICT), proved to be a game-changer for photovoltaic properties. Building on these results, we explored an innovative parallel tandem cell (PT-DSSC) configuration. By connecting separate cells containing N719 and MS-1 sensitizers, we achieved a record efficiency of 12.89% with enhanced short-circuit current density (JSC) and open-circuit voltage (VOC)compared to single-dye cells. This study highlights the potential of molecular engineering in organic sensitizers and device optimization to enhance DSSC performance, paving the way for further advancements in solar cell technology.
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Organic photovoltaic (OPV) cells are at the forefront of sustainable energy generation due to their lightness, flexibility, and low production costs. These characteristics make OPVs a promising solution for achieving sustainable development goals. However, predicting their lifetime remains challenging task due to complex interactions between internal factors such as material degradation, interface stability, and morphological changes, and external factors like environmental conditions, mechanical stress, and encapsulation quality. In this study, we propose a machine learning-based technique to predict the degradation over time of OPVs. Specifically, we employ multi-layer perceptron (MLP) and long short-term memory (LSTM) neural networks to predict the power conversion efficiency (PCE) of inverted organic solar cells (iOSCs) made from the blend PTB7-Th:PC70BM, with PFN as the electron transport layer (ETL), fabricated under an N2 environment. We evaluate the performance of the proposed technique using several statistical metrics, including mean squared error (MSE), root mean squared error (rMSE), relative squared error (RSE), relative absolute error (RAE), and the correlation coefficient (R). The results demonstrate the high accuracy of our proposed technique, evidenced by the minimal error between predicted and experimentally measured PCE values: 0.0325 for RSE, 0.0729 for RAE, 0.2223 for rMSE, and 0.0541 for MSE using the LSTM model. These findings highlight the potential of proposed models in accurately predicting the performance of OPVs, thus contributing to the advancement of sustainable energy technologies.
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Partial substitution of cations is crucial for suppressing harmful defects in Cu2ZnSn(S,Se)4 thin-film solar cells. In this study, based on the mixed n-butylammonium and butyrate solution system, the alloyed Cu2CoxZn1-xSn(S,Se)4 phase can be prepared by substituting Zn2+ with Co2+, which can suppress harmful defects and optimize the crystallinity of the Cu2ZnSn(S,Se)4 absorption layer, and improve the photoelectric conversion efficiency (PCE) of devices. By systematic investigation of the impact of Co content on the performance of devices, the optimal substitution amount of Zn2+ with Co2+ is 0.05. At this time, PCE, the open-circuit voltage (VOC), current density (JSC), and fill factor (FF) of the devices can reach 9.0%, 416 mV, 33.87 mA/cm2, and 64%, respectively. It is the first time that the replacement of Zn2+ with Co2+ is applied to optimize PCE of CZTSSe solar cells. The excellent results also demonstrate that the substitution of Zn2+ with Co2+ can become a new approach for further performance optimization of Cu2ZnSn(S,Se)4 solar cells.
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Hybrid organic-inorganic lead halide perovskite solar cells (PSCs) have rapidly emerged as a promising photovoltaic technology, with record efficiencies surpassing 26%, approaching the theoretical Shockley-Queisser limit. The advent of all-perovskite tandem solar cells (APTSCs), integrating Pb-based wide-bandgap (WBG) with mixed Sn-Pb narrow-bandgap (NBG) perovskites, presents a compelling pathway to surpass this limit. Despite recent innovations in hole transport layers (HTLs) that have significantly improved the efficiency and stability of lead-based PSCs, an effective HTL tailored for Sn-Pb NBG PSCs remains an unmet need. This review highlights the essential role of HTLs in enhancing the performance of Sn-Pb PSCs, focusing on their ability to mitigate non-radiative recombination and optimize the buried interface, thereby improving film quality. The distinct attributes of Sn-Pb perovskites, such as their lower energy levels and accelerated crystallization rates, necessitate HTLs with specialized properties. In this study, the latest advancements in HTLs are systematically examined for Sn-Pb PSCs, encompassing organic, self-assembled monolayer (SAM), inorganic materials, and HTL-free designs. The review critically assesses the inherent limitations of each HTL category, and finally proposes strategies to surmount these obstacles to reach higher device performance.
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In the quest for sustainable and renewable energy sources, researchers and engineers have explored innovative technologies to harvest energy from various environmental sources. Dielectric elastomer generators (DEGs) with high energy harvesting performance have been proven to be promising energy collectors, but achieving a high dielectric constant (ε') and low electrical conductivity (EC) under high electric fields of dielectric elastomer (DE) simultaneously is a struggle, which poses significant challenges. In this study, high-content carboxyl group-grafted liquid polybutadiene (HCPB) is synthesized and then adopted as an organic dielectric filler to blend and cocross-link with a butadiene rubber (BR) matrix to prepare DE composites with high energy harvesting performance. The introduction of carboxyl groups enhances polarization while trapping free Al3+ in the matrix, which revolutionarily achieves a significant increase in ε' under extremely low EC. Ultimately, the contradiction between increased ε' and decreased EC under high electric fields is reconciled, resulting in a 30 HCPB/BR composite with high energy density (w = 91.9 mJ/cm3) and fine power conversion efficiency (PCE = 24.1%). This advancement paves the way for the development of HCPB/BR composite-based DEGs with enhanced ε' and energy harvesting performance.
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Significant challenges in ensuring long-term stability, addressing environmental safety issues, and improving efficiency have hindered the commercialization of inverted Pb-based halide perovskite solar cells (PeSCs). One reasonable approach to addressing these issues is to place an effective buffer layer between the perovskite active layer and the electrode. In this study, we demonstrate the use of crown ether, di-tert-butyl dibenzo-18-crown-6, as a single buffer layer to improve the efficiency, long-term stability, and environmental safety of PeSCs for the first time. The crown ether buffer layer suppressed Ag diffusion from the Ag metal electrodes, thereby improving the performance and lifetime of the device. In addition, it effectively captures Pb ions that may leak into the environment during the whole lifetime of devices, thereby enhancing the environmental safety of PeSCs. Furthermore, PeSCs incorporating crown ethers as buffer layers demonstrated enhanced stability in a nitrogen atmosphere and achieved a high power conversion efficiency of 22.8%. Consequently, this crown ether buffer layer offers an effective and straightforward strategy capable of achieving efficient, stable, and environmentally safe PeSCs.
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The perovskite materials are broadly incorporated into optoelectronic devices due to a number of advantages. Their rapid technological progress is related to the relatively simple fabrication process, low production cost and high efficiency. Significant improvement is made in the light emitting, detection performance and device design especially operating in the visible and near-infrared regions. This review presents the status and possible future development of the perovskite devices such as solar cells, photodetectors, and light-emitting diodes. The fundamental properties of perovskite materials related to their effective device applications are summarized. Since the development of the perovskite technology is mainly driven by the revolutionary evolution of the semiconductor perovskite solar cell as a robust candidate for next-generation solar energy harvesting, this topic is considered first. The device engineering of various perovskite photodetector structures, including perovskite quantum dot photodetectors, is then discussed in detail. Their performance is compared with the current commercial photodetectors available on the global market together with their challenges. Finally, the considerable progress in the fabrication of the perovskite light-emitting diodes with external quantum efficiency exceeding 20% is presented. The paper is completed in an attempt to determine the development of perovskite optoelectronic devices in the future.
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Perovskite quantum dot solar cells (PQDSCs), as the promising candidate for the next generation of solar cell, have garnered the significant attention over the past decades. However, the performance and stability of PQDSCs are highly dependent on the properties of interfaces between the perovskite quantum dots (PQDs) and the other layers in the device. This work provides a brief overview of PQDSCs, including the synthesis of PQDs, the characteristics and preparation methods of PQDs, the photoelectric properties as the light absorption layer and optimization methods for PQDSCs with high efficiency. Future directions and potential applications are also highlighted.
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Semitransparent perovskite solar cells (ST-PSCs) have opened up new applications in tandem devices and building-integrated photovoltaics. Decreasing the thickness of the perovskite film makes it feasible to fabricate semitransparent perovskite layers. However, the formation of high-quality thin perovskite films has been a challenge during the film manufacturing process since the crystallization dynamics of thinner (<200 nm) films are different from that of thick films. In this article, we demonstrate a feasible method to fabricate a thinner layer of highly crystalline perovskites with low defect density for efficient ST-PSCs by introducing N-Ethylbenzylamine (EBA) to modify halide perovskites through Lewis acid-base interaction. As a result, a semitransparent solar cell based on EBA-treated perovskite with a film thickness of only â¼190 nm exhibits a high power conversion efficiency (PCE) of 14.77%, an average visible transmittance (AVT) of 13.2%, and an excellent light utilization efficiency (LUE) of 1.95%, which is the highest value in the ST-PSCs with Au as the electrode. Our findings highlight the effectiveness of the EBA additive in improving the photovoltaic performance of ST-PSCs, offering valuable insights into developing efficient and transparent photovoltaic technologies.
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Dipole moment arrangement in organic semiconductors plays a critical role in affecting the intermolecular packing, determining optoelectronic properties and device performance. Here, to get the desired fill factor (FF) values in organic solar cells (OSCs), the local dipole of non-fullerene acceptors (NFAs) is modulated by changing the molecular asymmetries. Two NFAs, AA-1 and AA-2 are designed and synthesized, which have different substitutions of alkyl and alkoxyl groups. The unidirectional asymmetry in AA-2 creates distinct local dipoles, while the bidirectional asymmetry in AA-1 mitigates dipole variation. Despite the minimal impact on monomolecular properties, the local dipole moment significantly influences terminal group packing modes in the film state. This, in turn, enhances the relative dielectric constant, prolongs exciton lifetime, and reduces sub-bandgap defect states. Consequently, PBDB-TF:AA-2-based OSCs achieve an exceptional FF of 0.830 and a power conversion efficiency (PCE) of 18.3%, with a ternary device reaching a PCE of 19.3%. This work highlights the potential of dipole modulation in material design to get ideal FF values for high-performance OSCs.
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High-performance organic solar cells often rely on halogen-containing solvents, which restrict the photovoltaic industry. Therefore, it is imperative to develop efficient organic photovoltaic materials compatible with halogen-free solvents. Herein, a series of benzo[a]phenazine (BP)-core-based small-molecule acceptors (SMAs) achieved through an isomerization chlorination strategy is presented, comprising unchlorinated NA1, 10-chlorine substituted NA2, 8-chlorine substituted NA3, and 7-chlorine substituted NA4. Theoretical simulations highlight NA3's superior orbit overlap length and tight molecular packing, attributed to interactions between the end group and BP unit. Furthermore, NA3 demonstrates dense 3D network structures and a record electronic coupling of 104.5 meV. These characteristics empower the ortho-xylene (o-XY) processed PM6:NA3 device with superior power conversion efficiency (PCE) of 18.94%, surpassing PM6:NA1 (15.34%), PM6:NA2 (7.18%), and PM6:NA4 (16.02%). Notably, the significantly lower PCE in the PM6:NA2 device is attributed to excessive self-aggregation characteristics of NA2 in o-XY. Importantly, the incorporation of D18-Cl into the PM6:NA3 binary blend enhances crystallographic ordering and increases the exciton diffusion length of the donor phase, resulting in a ternary device efficiency of 19.75% (certified as 19.39%). These findings underscore the significance of incorporating new electron-deficient units in the design of efficient SMAs tailored for environmentally benign solvent processing of OSCs.
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Additive engineering plays a pivotal role in achieving high-quality light-absorbing layers for high-performance and stable perovskite solar cells (PSCs). Various functional groups within the additives exert distinct regulatory effects on the perovskite layer. However, few additive molecules can synergistically fulfill the dual functions of regulating crystallization and passivating defects. Here, we custom-synthesized 2-ureido-4-pyrimidone (UPy) organic small molecules with diverse functional groups as additives to modulate crystallization and defects in perovskite films via the Michael addition reaction. Theoretical and experimental investigations demonstrate that the -OH groups in UPy exhibit significant effects in fixing uncoordinated Pb2+ ions, passivation of lead-iodide antisite defects, alleviating hysteresis, and reducing non-radiative recombination. Furthermore, the enhanced C=O and -NH2 motifs interact with the A-site cation via hydrogen bonding, which relieves residual strain and adjusts crystal orientation. This strategy effectively controls perovskite crystallization and passivates defects, ultimately enhancing the quality of perovskite films. Consequently, the open-circuit voltage of the UPy-based p-i-n PSCs reaches 1.20â V, and the fill factor surpasses 84 %. The champion device delivers a power conversion efficiency of 25.75 %. Remarkably, the unencapsulated device maintained 96.9 % and 94.5 % of its initial efficiency following 3,360â hours of dark storage and 1,866â hours of 1-sun illumination, respectively.
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As the simplest oligomeric acceptors, dimerized acceptors (DAs) are easier to synthesize, and more importantly, they can retain good intermolecular interaction and photovoltaic properties of their parent small-molecule acceptors (SMAs). Nevertheless, currently most efficient DAs are derived from banana-shaped acceptors and they might suffer from inferior device stability with high diffusion coefficients. Herein, we design and synthesize two planar DAs (DMT-FH and DMT-HF) by bridging two linear-shaped M-series SMAs with a thiophene unit. The effects of fluorination position on the diffusion coefficients, power conversion efficiencies (PCEs) and stability of the DAs are systematically studied. Our results suggest that DMT-HF with fluorination on the ending indanone groups shows enhanced intermolecular interactions, improved PCE and stability compared with the counterpart (DMT-FH) with fluorination on the central indanone groups. Further optimization on the DMT-HF-based devices yields an outstanding PCE of 17.17 %, which is the highest among all linear-shaped SMA-based DAs. Notably, with the low diffusion coefficient (3.36×10-24â cm2 s-1) of DMT-HF, the resulting device retains over 93 % of the initial PCE after 5000â h of continuous heating at 85 °C, suggesting its excellent thermal stability. The results highlight the importance of intermolecular interaction and fluorination for achieving efficient and stable polymer solar cells.
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Volatile solid additives have emerged as a promising strategy for enhancing film morphology and promoting the power conversion efficiency (PCE) of organic solar cells (OSCs). Herein, a series of novel polycyclic aromatic additives with analogous chemical structures, including fluorene (FL), dibenzothiophene (DBT), and dibenzofuran (DBF) derived from crude oils, are presented and incorporated into OSCs. All these additives exhibit strong interactions with the electron-deficient terminal groups of L8-BO within the bulk-heterojunction OSCs. Moreover, they demonstrate significant sublimation during thermal annealing, leading to increase free volumes for the rearrangement and recrystallization of L8-BO. This phenomenon leads to an improved film morphology and an elevated glass-transition temperature of the photoactive layers. Consequently, the PCE of the PM6:L8-BO blend has been boosted from 16.60% to 18.60% with 40 wt% DBF additives, with a champion PCE of 19.11% achieved for ternary PM6:L8-BO:BTP-eC9 OSCs. Furthermore, the prolonged shelf and thermal stability have been observed in OSCs with these additives. This study emphasizes the synergic effect of volatile solid additives on the performance and thermal stability of OSCs, highlighting their potential for advancing the field of photovoltaics.
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This study focuses on the theoretical aspects of third-generation perovskite solar cells (PSC), with the aim of replacing traditional silicon-based counterparts. With potential for higher efficiency and low manufacturing costs, perovskite cells offer unique crystallographic structures allowing adjustments to photoluminescence wavelength. This research addresses challenges in cost-effective solar spectrum utilization and optimization of parameters, device architecture, and materials for high-efficiency cells. In this study, we simulated a perovskite-based solar cell (CH3NH3SnI3) using solar cell capacitance simulator-one dimension simulator under AM 1.5G illumination. The chosen electron transport layer is TiO2, and hole transport layer is CH3NH3SnBr3. The simulation explores variations in layer thickness, defect concentration, interface defects, doping concentration and electron affinity. Additionally, we analyzed the impact of back metal contact work function and temperature variations. Results indicate optimal absorber layer thickness at 0.5µm. Reduced defect concentrations, increased doping concentration and a higher work function for the back contact, enhance efficiency of PSC. The initial parameters yielded a 19.79% efficiency based on base values before optimization, which increased to 26.66% after optimization. According to the latest NREL data, the highest reported efficiency for PSC is 26.1%. This research provides insights into perovskite-based solar cell design for enhanced efficiency.