Top Subcell Research Articles

Feasibility of Exceeding 20% Efficiency for Kesterite/c-Silicon Tandem Solar Cells Using an Alternative Buffer Layer: Optical and Electrical Analysis

Tandem solar cells have the potential to be more efficient than the Shockley–Queisser limit imposed on single junction cells. In this study, optical and electrical modeling based on experimental data were used to investigate the possibility of boosting the performance of kesterite/c-Si tandem solar cells by inserting an alternative nontoxic TiO2 buffer layer into the kesterite top subcell. First, with SCAPS-1D simulation, we determined the data reported for the best kesterite (CZTS (Eg = 1.5 eV)) device in the experiments to be used as a simulation baseline. After obtaining metric parameters close to those reported, the influence on the optoelectronic characteristics of replacing CdS with a TiO2 buffer layer was studied and analyzed. Different top subcell absorbers (CZTS0.8Se0.2 (Eg = 1.4 eV), CZTS (Eg = 1.5 eV), CZTS (Eg = 1.6 eV), and CZT0.6Ge0.4S (Eg = 1.7 eV)) with different thicknesses were investigated under AM1.5 illumination. Then, to achieve current matching conditions, the c-Si bottom subcell, with an efficiency at the level of commercially available subcells (19%), was simulated using various top subcells transmitting light calculated using the transfer matrix method (TMM) for optical modeling. Adding TiO2 significantly enhanced the electrical and optical performance of the kesterite top subcell due to the decrease in parasitic light absorption and heterojunction interface recombination. The best tandem device with a TiO2 buffer layer for the top subcell with an optimum bandgap equal to 1.7 eV (CZT0.6Ge0.4S4) and a thickness of 0.8 µm achieved an efficiency of approximately 20%. These findings revealed that using a TiO2 buffer layer is a promising way to improve the performance of kesterite/Si tandem solar cells in the future. However, important optical and electrical breakthroughs are needed to make kesterite materials viable for tandem applications.

Improving current-matching in textured perovskite/silicon tandem solar cells via a thickness control strategy

This study presents an analysis of a two-terminal tandem solar cell that integrates metal-doped, lead-free double Cs2AgBi0.75Sb0.25Br6 perovskite with silicon to enhance overall energy conversion efficiency. This study explores how the thicknesses of the top and bottom sub-cells affect current-matching in two-terminal tandem perovskite/silicon solar cells with two separate planar and textured configurations. Using numerical modeling in MATLAB, and considering dominant recombination effects, we calculated the performance parameters of the device. We investigated the optical and electrical properties of textured tandem structures, focusing on current- matching and the influence of layer thickness on device performance. Given the complexity, time, and expense involved in constructing tandem solar cells, being able to analytically determine the thickness at which current-matching occurs can be highly advantageous. This approach offers the benefit of providing a precise analytical relationship for this purpose. Our findings demonstrate that increasing the top cell thickness enhances current density and power conversion efficiency, but at the cost of the bottom cell’s efficiency due to increased light absorption. Moreover, we discovered a nearly linear behavior between the thickness of the top and bottom cells for achieving current-matching. The study highlights the critical balance required to optimize layer thicknesses, thereby improving the design and performance of tandem solar cells. These insights are significant as they pave the way for more efficient and cost-effective tandem solar cell designs in the future, potentially accelerating the adoption of advanced photovoltaic technologies. The results show good agreement with experimental data, validating our model.

Wide‐Range Wavelength Light Scattering from Black Silicon Layers: Profits for Perovskite/Si Tandem Solar Cells

This study investigates the optical properties (light reflectance, absorptance, transmittance, and scattering) of black silicon (b‐Si) layers formed using reactive ion etching method. The corresponding spectra are determined across the visible, near‐infrared, and near‐ultraviolet wavelength ranges (250–1400 nm). It is demonstrated that b‐Si layers reduce the reflectance, and increase the absorptance and light scattering due to the disordered distribution of the nanoneedles. Increasing the etching duration strengthens this trend. It is shown that b‐Si layers etched for 10 min can be considered perfect light scatterers upon reflection at wavelengths less than 700 nm. Based on the obtained results, the possible profits of light scattering from the b‐Si interlayer for perovskite/Si tandem solar cells are analyzed. It is substantiated that the b‐Si interlayer can increase the useful absorptance not only within the bottom Si solar subcell but also in the top perovskite solar subcell. The prospects for future research directions and challenges are also provided.

Opto-electrical study of 4T perovskite-chalcogenide tandem solar cell with the addition of quasi-2D perovskite as capping layer of 3D perovskite layer

This study presents a four-terminal (4T) perovskite-chalcogenide tandem solar cell (TSC) that includes quasi-2D perovskite material in the top sub-cell in order to provide a stable structure, and the bottom sub-cell contains Zn(O,S,OH) material to provide a nontoxic buffer layer. First, a reference TSC with a total power conversion efficiency (PCE) of 26.48% is modeled, using MAPbI3 and CIGSSe as 3D perovskite and chalcogenide absorber layers (ALs), respectively. Next, two structures are designed to produce a stable SC using the Ruddlesden Popper (RP) quasi-2D perovskite materials, which have the chemical formula BA2MAm−1PbmI3m+1, m = 2–5. The initial structure uses quasi-2D perovskites in place of the 3D perovskite AL. According to the results, BA2MAPb2I7 represents the maximum PCE of 16.00%, 10.48% less than previously. This is caused by quasi-2D materials’ high Eg and low carrier mobility. In the second structure, 3D perovskite AL is capped with the quasi-2D perovskites. In terms of attaining maximum PCE, the optimal TSC is found for BA2MA3Pb4I13 with a PCE of 25.80%. Compared to the initial structure, this one’s PCE increased by 61.25%. In order to boost PCE, a 80 nm-thick anti-reflection (AR) layer is added to the second structure, and the PCE increased to 27.48%. Therefore, the final TSC is proposed as a 4T quasi-2D/3D perovskite-chalcogenide TSC that is stable, and has nontoxic buffer layer, with 3.78% more PCE than the reference structure.

(Invited) Perovskite/Perovskite Tandem Photoelectrodes for Unassisted Water Splitting

The bandgap tunability and low-temperature processing make halide perovskites excellent candidates for achieving efficient and cost-effective tandem devices for solar cells and solar-driven water electrolysis devices. Here, we report our progress on fabricating perovskite/perovskite tandem cells consisting of two solution-processed perovskite subcells for unassisted water-splitting applications. The perovskite/perovskite tandem photoelectrodes are achieved by monolithically integrating a wide-bandgap (1.7 – 2.1 eV) Pb-based mixed-halide (Br-I) perovskite top subcell and a narrower-bandgap (1.25 - 1.55 eV) bottom subcell based on Pb-based or mixed Pb-Sn iodide perovskites. Varying the halide perovskite composition for each subcell enables us to tailor the photovoltaic performance of the tandem devices. We demonstrate that perovskite/perovskite tandem solar cells can deliver open-circuit voltages of more than 2 V. The high photovoltage provides a sufficient overpotential to drive unassisted photoelectrochemical (PEC) water splitting with a solar-to-hydrogen conversion efficiency of more than 15%. After applying water-impermeable encapsulants, the perovskite/perovskite photoelectrodes can successfully operate in an aqueous environment and enable a long operational lifetime.

A new CsPbI2Br/CuZnSnSSe/Si tandem solar cell with higher than 32 % efficiency

To avoid Shockley-Queisser limit in single p-n junctions, tandem solar cells were proposed. A new tandem cell is simulated here using the 1-dimensional SCAPS. The new cell combines two reported single solar cells together, aiming at achieving high performance by optimizing various layer characteristics. The bottom sub-cell is Mo/Si(p)/CZTSSe(p)/CdS(n)/ZnO(i)/ZnO(Al), where ZnO is an electrodeposited transparent-conductor oxide, with high UV transmittance, ZnO(i) is intrinsic layer, CZTSSe/Si is bi-absorber layer of p-CuZnSnSSe and p-Si, Mo is back contact. The optimized sub-cell exhibits a high fill factor of 85.18 % with overall efficiency 20 %. Based on literature, a perovskite CsPbI2Br layer is included in the top sub-cell Cu2O(HTL)/CsPbI2Br)/TiO2(ETL), where Cu2O is a hole-transport layer and TiO2 is electron-transport layer. The top sub-cell layers have been carefully selected for best alignment. Matching and optimizing various parameters in the two sub-cells is a simulation challenge. Therefore, layers in the two sub-cells have been studied separately, keeping in mind the proper combinations between various layers. With optimized layer thicknesses and band gaps, together with proper alignment of band edges, the proposed tandem solar cell exhibits high characteristics of 80 % fill factor and higher than 32 % overall efficiency.

Advancements and Challenges in Wide‐Bandgap Perovskite Solar Cells: From Single Junction to Tandem Solar Cells

The exceptional optoelectronic performance and cost‐effectiveness of manufacturing have propelled organic–inorganic hybrid perovskite solar cells (PSCs) into the spotlight within the photovoltaic community. Currently, the single‐junction PSCs have achieved a certified power conversion efficiency surpassing 26%, edging closer to the illustrious Shockley–Queisser theoretical limit. To further enhance device performance, researchers are currently directing their attention toward the integration of wide‐bandgap (WBG) perovskites (Eg > 1.60 eV) as top subcells in conjunction with narrow‐bandgap materials, such as perovskite, crystalline silicon, and copper indium gallium selenium, to construct multijunction tandem devices that maximize solar spectral utilization and minimize thermal losses. However, WBG perovskites encounter challenges associated with suboptimal crystal quality, high defect density, and severe phase separation, leading to significant voltage losses and inferior performance. In this regard, extensive research has been conducted, yielding significant findings. This review article summarizes the advancements in composition engineering, additive engineering, and interface engineering of WBG PSCs. Furthermore, the applications of WBG PSCs in various tandem solar cells and their development are discussed. Finally, future prospects for the development of WBG PSCs are outlined.

Boosting All-Perovskite Tandem Solar Cells by Revitalizing the Buried Tin-Lead Perovskite Interface.

Narrow-bandgap (NBG) mixed tin-lead (Sn-Pb) perovskite solar cells (PSCs) serve as crucial top subcells in all-perovskite tandem solar cells (TSCs). However, the prevalent use of poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) hole transport layers (HTLs) in NBG PSCs compromises device efficiency and stability. To address this, the study proposes a revitalizing strategy for the buried interface of Sn-Pb perovskites by directly immersing acetylcholine chloride (ACh) into PEDOT: PSS. ACh acts as a proficient "diver," not only modulating the bottom PEDOT: PSS HTLs but also facilitating the reconstruction of the buried interface and significantly enhancing the quality of the top perovskite layers. This intervention with ACh prevents Sn2+ oxidation, mitigates buried defects, and encourages the growth of large, densely packed grains within Sn-Pb perovskites. Consequently, the optimized NBG PSCs exhibit significantly improved hole transport and reduced carrier recombination, achieving a steady-state efficiency of 22.98% with enhanced stability. Furthermore, these optimized NBG Sn-Pb cells enable highly efficient two-terminal and four-terminal all-perovskite TSCs, boasting steady-state efficiencies of 27.54% (certified at 26.41%) and 28.01%, respectively. This study emphasizes the importance of optimizing NBG PSCs through buried interface reconstruction, propelling the advancement of all-perovskite TSCs.

A scalable method for fabricating monolithic perovskite/silicon tandem solar cells based on low-cost industrial silicon bottom cells

Tandem solar cells composed of perovskite and silicon (PVSK/Si TSCs) exhibit significant potential for improving the power conversion efficiency (PCE) and reducing the levelized cost of electricity. Currently, most tandem cells demonstrating high efficiencies utilize costly float zone (FZ) silicon wafers, which pose limitations for large-scale production due to their high expense. This study presents a scalable approach for manufacturing perovskite/silicon tandem solar cells using industrial silicon bottom cells. We employ a double-layer intrinsic amorphous silicon passivation layer to enhance the carrier lifetime of the bottom silicon cell. Additionally, we introduce a novel indium oxide doped with transition metals (IMO) transparent electrode to enhance near-infrared (NIR) light absorption. To achieve silicon bottom cells with a polished front surface, we utilize a cost-effective and time-saving saw damage etching process. The perovskite absorber is then deposited on the polished surface using slot-die coating. Furthermore, we coat the perovskite absorber with a mixed solution of FAI and mF-PEAI via slot-die coating to eliminate excess PbI2 on the surface and passivate surface defects. Through the integration of top and bottom sub-cells, we obtained a PCE exceeding 24.22 % from a 5 cm × 5 cm TSCs device (with an aperture area of 3.8 cm × 3.8 cm) and a PCE of 28.68 % from a 2.5 cm × 2.5 cm TSCs device (with an aperture area of 1 cm × 1 cm).

Effects of subcell bandgap matching on the performance of perovskite/Cu(In,Ga)Se2 tandem solar cells

The tandem solar cell is composed of a wide bandgap top subcell and a narrow bandgap bottom subcell, which is a promising technology to surpass the theoretical efficiency of single-junction solar cell. Since the currents are generated by photo-generated carriers and the two subcells are united in series, the absorber thickness should be adjusted with the change of the bandgaps to ensure that the two subcells have the same currents. In this study, the impacts of subcell bandgaps on perovskite/Cu(In,Ga)Se2 tandem solar cells were investigated using SCAPS-1D. For perovskite top subcells, the short-circuit current and power conversion efficiency increased with the absorber thickness increasing, and photons in short-wavelength part could be absorbed by perovskite solar cells, while photons in long-wavelength part were almost not absorbed. In tandem solar cells, the increasing bandgap of top subcell and the decreasing bandgap of bottom subcell required higher top subcell thickness to achieve the current matching condition. The top subcell bandgap needed to be wide enough and the bottom subcell bandgap needed to be narrow enough to get the same current. The efficiency increased as the top subcell bandgap increased to 1.7 eV, and started to decline with the further increase of bandgap. Moreover, the efficiency increased as the bottom subcell bandgap increased up to 1.28 eV, but decreased when the bandgap kept increasing. The optimized tandem solar cell achieved the highest efficiency of 32.71 % with the top subcell bandgap of 1.7 eV and the bottom subcell bandgap of 1.28 eV.

Comprehensive design and analysis of thin film Sb2S3/CIGS tandem solar cell: TCAD simulation approach

This research presents a design and analysis of a tandem solar cell, combining thin film wide bandgap Sb2S3 (1.72 eV) and narrow bandgap CIGS (1.15 eV) for the top and bottom sub-cells, respectively. The integration of all thin film layers enhances flexibility, rendering the tandem solar cell suitable for applications such as wearable electronics. To optimize the power conversion efficiency (PCE) of the tandem solar device, advanced technology computer-aided design (TCAD) simulation tools are employed to estimate loss mechanisms and fine-tune parameters for each layer. An experimentally validated optoelectronic model is introduced, calibrated and validated against fabricated reference solar cells for the individual top and bottom cells. The calibrated model is then utilized to propose optimization routines for the Sb2S3/CIGS tandem solar cell. The initial tandem cell exhibits a J SC of 15.72 mA cm−2 and a PCE of 15.36%. The efficiency drop in the tandem configuration is identified primarily in the top cell. A systematic optimization process for the top cell is initiated, exploring various configurations, including HTL-free and ETL-free setups. Moreover, an np homojunction structure for the top cell is proposed. Optimization routines are applied that involve determining optimal thickness and doping concentration of the n-layer, investigating the effect of p-layer doping concentration, and exploring the influence of the work function of the front contact. As a result, the tandem cell efficiency is significantly improved to 23.33% at the current matching point (CMP), with a J SC of 17.15 mA cm−2. The findings contribute to the advancement of thin-film tandem solar cell technology, showcasing its potential for efficient and flexible photovoltaic applications.

Enhanced Efficiency and Stability of Wide‐Bandgap Perovskite Solar Cells Via Molecular Modification with Piperazinium Salt

AbstractWide‐bandgap (WBG) perovskite solar cell (PSC) plays a pivotal role as the top subcell in all‐perovskite tandem solar cells (TSCs), facilitating the absorption of high‐energy photons and affording a large open‐circuit voltage (VOC). Nonetheless, the stability and efficiency of WBG PSCs are constrained by light‐induced halide segregation and non‐radiative recombination losses. In this study, this work presents an approach of utilizing 2‐methylpiperazinium bromide (2‐MePBr) via interfacial engineering to realize high‐efficiency WBG (1.77 eV) PSCs. The C─NH─C functional group in 2‐MePBr, serving as an electron donor, can interact with under‐coordinated lead defects at the perovskite surface. Consequently, the treatment with 2‐MePBr mitigates interfacial non‐radiative recombination, enhances charge transport, inhibits ion migration, and thus delivers an improved power conversion efficiency (PCE) of 19.30% with a VOC of 1.29 V, and a fill factor of 83.08%. Notably, the WBG PSCs manifest enhanced stability, preserving 80% of the initial PCE after 337 h of continuous operation under 1 sun illumination at the maximum power point. Furthermore, the all‐perovskite TSCs based on this WBG subcell achieve a PCE of 27.47%, showing its promising application in perovskite‐based tandem solar cells.

A comprehensive simulation study of multi-junction solar cell

This study conducts comprehensive simulation analysis of typical triple-junction solar cells using Silvaco ATLAS. Initially, modeling and simulation of the typical triple-junction solar cells under the AM1.5 solar spectrum at 300 K are performed to characterize various performance parameters of the cells under one sun illumination. Subsequently, the impact of the thickness of the top and middle cell layers on the efficiency of the cells is analyzed. Additionally, the influence of doping concentration errors in individual sub-cells on the overall power deviation of the cells is investigated. Moreover, Al0.9Ga0.1As is employed to replace AlInP as the top FSF (Front Surface Field). Furthermore, the study analyzes the variation of internal radiation efficiency of the top and middle sub-cells of the solar cells with concentration factor and bias voltage. Finally, an assessment is made on the effects of different positions and densities of interface defects, as well as the introduction of class-acceptor Gaussian distribution state levels induced by defects, on the performance of the solar cells. The results indicate that this study provides valuable insights for optimizing multi-junction solar cells and analyzing internal physical phenomena.

Utilizing Metal Oxide Thin Films for Device Engineering of Solution-Processed Organic Multi-Junction Solar Cells

Electron and hole transporting layers play a major role in high-performance and stable organic-based optoelectronic devices. This paper demonstrates detailed device engineering of multi-junction organic photovoltaics built on two different metal oxide-based electron and hole transport (buffer) layers prepared by thermal or solution-processed methods. The main focus is on the device processing parameters as well as practical details of preparation of buffer layers to give the research community a clear, step-by-step recipe to successfully replicate and build series and parallel connected multi-junction solution-based organic solar cells for their needs. Here, the recipes and deposition conditions of two metal oxide buffer layers are presented in detail, based on basic commercially available materials and tools, to achieve well-engineered tandem (multi-junction) solution-processed organic solar cells. The buffer layers have appropriate energy levels for electrical selectivity of anode and cathode electrodes, and they are highly stable and chemically compatible with processing of solution-based polymer solar cells. To demonstrate the engineering steps of multi-junction devices, the PCE10:PC70BM blend is used as the active layer for all subcells. Then, to improve the power conversion efficiency of the single-junction photovoltaic device, PCE10:PC70BM blend is used in combination with DPPx:PC70BM with different absorption spectra for bottom and top subcell active layers. An optimized series tandem device with 10.6% power conversion efficiency is demonstrated. Generally, the device structures reported here can also be used for other types of optoelectronic devices, such as light emitting diodes and photodetectors.

Phase-stable wide-bandgap perovskites enabled by suppressed ion migration

Wide-bandgap (>1.7 eV) perovskites suffer from severe light-induced phase segregation due to high bromine content, causing irreversible damage to devices stability. However, the strategies of suppressing photoinduced phase segregation and related mechanisms have not been fully disclosed. Here, we report a new passivation agent 4-aminotetrahydrothiopyran hydrochloride (4-ATpHCl) with multifunctional groups for the interface treatment of a 1.77-eV wide-bandgap perovskite film. 4-ATpH+ impeded halogen ion migration by anchoring on the perovskite surface, leading to the inhibition of phase segregation and thus the passivation of defects, which is ascribed to the interaction of 4-ATpH+ with perovskite and the formation of low-dimensional perovskites. Finally, the champion device achieved an efficiency of 19.32% with an open-circuit voltage (VOC) of 1.314 V and a fill factor of 83.32%. Moreover, 4-ATpHCl modified device exhibited significant improved stability as compared with control one. The target device maintained 80% of its initial efficiency after 519 h of maximum power output (MPP) tracking under 1 sun illumination, however, the control device showed a rapid decrease in efficiency after 267 h. Finally, an efficiency of 27.38% of the champion 4-terminal all-perovskite tandem solar cell was achieved by mechanically stacking this wide-bandgap top subcell with a 1.25-eV low-bandgap perovskite bottom subcell.

Research Progress of Semi-Transparent Perovskite and Four-Terminal Perovskite/Silicon Tandem Solar Cells

Perovskite/silicon tandem solar cells are of great interest due to their potential for breaking the Shockley-Queisser limit of single-junction silicon solar cells. Perovskite solar cells are widely used as the top subcells in perovskite/silicon tandem solar cells due to their high efficiency and lower fabrication cost. Herein, we review the semi-transparent perovskite solar cell in terms of the mechanisms of their translucent structure, transparent electrodes, charge transport layer, and component modification. In addition, recent progress in the research and development of 4T perovskite/silicon tandem solar cells is summarized, with emphasis on the influence of perovskite structure and silicon cells on the progress of tandem solar cells. Finally, we discuss the challenges associated with 4T perovskite/silicon tandem solar cells and suggest directions for the development of perovskite/silicon commercialization.

Two-step synthesis of antimony sulfide thin films: enhancement in physical properties through sulfurization

Recently, there has been an increase in the use of antimony sulfide (Sb2S3) in Si-based tandem solar cells as a potential absorber material for top sub-cells. The choice of the material stems from the favoured properties such as appropriate bandgap, simple binary composition, nontoxic elements, and long-term stability. However, the physical properties and practical applicability of these materials depend largely on their synthesis conditions. In this work, we investigate the role of sulfurization on the structural, morphological, compositional, and optical properties of Sb2S3 thin films deposited on soda-lime glass via a thermal evaporation technique. Sulfurization was performed on the as-prepared thin films in a customized Chemical Vapor Deposition (CVD) chamber at five different temperatures. Analysis of the crystallinity of the film using the x-ray diffraction technique illustrates the transformation of the film from impure, poor crystalline phase to phase-pure, and highly crystalline orthorhombic structure due to sulfurization. Scanning electron microscopic investigations of the samples revealed better grains with nanorods on the surface at a temperature of 400 °C. For the samples investigated here, the energy values estimated via density functional theory (DFT) calculations agreed well with the experimental data obtained from UV-visible absorption spectral studies. Additionally, it was observed that the desired near-stoichiometric Sb2S3 thin films could be achieved via sulfurization, and the presence of Sb2S3 in all samples was confirmed via Raman spectroscopic studies. Additionally, the defects and trap states of the prepared films were investigated using photoluminescence studies, and donor and acceptor defects were identified. Our study revealed that sulfur rich Sb2S3 films prepared at a sulfurization temperature of 400 °C produced the desired structure, morphology, and optical qualities for future photovoltaic applications.

Stability Challenges for a Highly Efficient Perovskite/Silicon Tandem Solar Cell: A Review

As the balance of system cost of photovoltaic (PV) installations governs the competitiveness of PV device market, next‐generation solar cells desire substantially enhanced power conversion efficiencies (PCEs). The single‐junction perovskite and Si solar cells have demonstrated PCEs beyond 26% and 25%, respectively. The tandem configuration has crossed the threshold posed by the shockley queisser limit by demonstrating the 33.9% PCE. However, the unresolved issues in the perovskite community from a stability perspective pose challenges for realizing highly efficient and stable perovskite–Si tandem solar cells (TSCs). This review highlights the current status of perovskite–Si TSC from a stability perspective besides elucidating the degradation mechanisms at the perovskite–Si at the cell and module level. A highly efficient perovskite–Si TSC needs optimization keeping view the specific requirements for tandem configuration like strain, current matching, and bandgap optimization between the top perovskite and bottom Si subcell. Various stressors affecting the efficiency of the perovskite–Si module, namely, reverse bias and hot spot formation, and delamination, highlight valuable insight to develop future strategies for the perovskite–Si TSC. Stability regimes for the single‐junction perovskite solar cell can provide the essential stepping stone but, modified stability regimes are inevitable.

Photonic Crystal Beam Splitter Electrode in Kesterite Tandem Solar Cells: A Numerical Approach

The majority of numerical research on kesterite tandem solar cells has predominantly focused on a two‐terminal (2T) configuration that utilizes an ideal tunnel junction. Herein, the performance of kesterite tandem solar cells by introducing a photonic crystal structure (1DPC) as intermediate layer in both three‐terminal (3T) and four‐terminal (4T) configurations is investigated. The photonic crystal (1DPC) is designed by stacking ITO and SiO2 layers with the terminal layer consisting of NiO. Optical properties of the 1DPC are modeled. This innovative approach offers several advantages. 1) The 1DPC selectively reflects lower wavelengths, effectively enhancing the short‐circuit current density (Jsc) of the top subcell, while the solar irradiance spectrum at higher‐wavelength optimum for the subcell is not affected. 2) The 1DPC serves as an intermediate electrode, needed for the 3T or 4T configuration. 3) Replacing the conventional Mo back contact with a NiO layer significantly boosts the open‐circuit voltage (Voc) of the top subcell. The findings demonstrate that these configurations exhibit higher performance compared to previously reported results. Furthermore, the utilization of 3T and 4T configurations, incorporating the 1DPC as an electrical beam splitter, provides an effective and accurate design compared to the 2T configuration using ideal tunnel junctions.

Optimization of Perovskite/Colloidal Quantum Dot Monolithic Tandem Solar Cell to Enhance Device Performance via Solar Cell Capacitance Simulator 1D

Tandem solar cells (TSCs) based on metal halide perovskites offer a route to increase power conversion efficiency (PCE). However, there are limited options for narrow‐bandgap bottom subcells. Colloidal quantum dots‐based solar cells are found attractive for this role. Herein, a cost‐effective two‐terminal (2T) monolithic TSC structure consisting of wide‐bandgap all‐inorganic perovskite top subcell and narrow‐bandgap chalcogenide PbS quantum dots bottom subcell is proposed. For optimization of the PCE of the tandem structure, standalone and tandem analysis are done in terms of variation of absorber layer thickness, total defect density, interfacial defect density, back metal contact, current density voltage (J–V) curves, external quantum efficiency, current matching, and tandem photovoltaic parameters. Optimized TSCs designed with the 530 nm/450 nm‐thick absorber layers of top/bottom sub cells result in of 19.28 mA cm−2, of 1.89 V, and PCE of 27.32%. It is found that performance of the device is very sensitive to the total defect density of the bottom subcell. Therefore, high PCE can be obtained by controlling the total defect density of the bottom subcell. This work motivates the experimental realization of low‐cost, high‐efficiency TSCs for further research.