Hybrid Tandem Solar Cells Research Articles

Advancements in Organic-Based Hybrid Tandem Solar Cells Considering Light Absorption and Spectral Matching of Organic Materials

Advancements in Organic-Based Hybrid Tandem Solar Cells Considering Light Absorption and Spectral Matching of Organic Materials

All-inorganic halide perovskites for air-processed “n–i–p” monolithic perovskite/organic hybrid tandem solar cells exceeding 23% efficiency

We are excited to report dynamic hot-air assisted ambient conditions processed metal ion-doped γ-CsPb(I1−xBrx)3 (Eg = 1.87 eV) wide bandgap in combination with a ternary bulk-heterojunction (Eg = 1.36 eV) narrow bandgap based monolithic hybrid tandem solar cells crossing 23% efficiency.

AgSCN as a new hole transporting material for inverted perovskite solar cells

A novel HTM based on silver thiocyanate (AgSCN) was designed to be useable in p-i-n perovskite solar cells (PSCs). With mass yield, the AgSCN was synthesized in the lab and elucidated by XRD, XPS, Raman spectroscopy, UPS, and TGA. The production of thin, highly conformal AgSCN films that allow for quick carrier extraction and the collection was made possible by a fast solvent removal approach. Photoluminescence experiments have shown that adding AgSCN has improved the ability to transfer charges between HTL and perovskite layer compared to PEDOT:PSS at the interface. Crystallographic discrepancies in the polycrystalline perovskite film are discovered upon further examination of the film's microstructure and morphology, pointing to the development of templated perovskite on the surface of AgSCN. In comparison to devices due to the well-known PEDOT:PSS, the open circuit voltage (VOC) is increased by AgSCN with its high work function by 0.1–1.14 V (1.04 V for PEDOT:PSS). With a power conversion efficiency (PCE) of 16.66%, a high-performance PSCs are effectively generated using CH3NH3PbI3 perovskite compared to 15.11% for controlled PEDOT:PSS devices. The solution-processed inorganic HTL was demonstrated employing straightforward in order to build durable and effective flexible p-i-n PSCs modules or their use as a front cell in hybrid tandem solar cells.

Analysis of hybrid tandem solar cell using neural network

In the 21st century, revolutions in the renewable energy sector have been accelerating at a rapid pace. It is due to the search for environment-friendly sources of energy and to fit the modus operandi of a sustainable society intended for the well-being of future generations. The solar energy sector is witnessing several attempts to increase the efficacy of solar energy systems. The ongoing research in Quantum Dot Solar Cells (QDSC), Perovskites and Carbon nanotubes leads to the advancement in natural energy. The QDSCs are a fairly interesting concept that aims to increase the efficiencies and costs of the solar cell. In this paper, the construction and working of a Tandem Solar Cell is analysed and the different design parameters are calculated. The cell is a monolithic hybrid integrated structure consisting of a low bandgap Colloidal Quantum Dot (CQD) back cell on top of an Organic Photovoltaic (OPV) cell. The hybrid tandem solar cell is simulated using MATLAB software and the various parameters are calculated using various experimentations. Further, a Levenberg-Marquardt training algorithm is used to train the experimented parameters for hybrid tandem solar cells. The training algorithm has been successfully used to accurately predict values for short circuit current density using three input parameters namely the open-circuit voltage and the thicknesses of the OPV and CQD, respectively. The various experimentation using ANN show that the experimental values are relatively matched with predicted results.

Organic/amorphous silicon hybrid tandem solar cell with PDPP3T as organic active layer

An organic/amorphous silicon(a-Si) hybrid tandem solar cell has been fabricated using poly(diketopyrrolopyrrole-terthiophene) (PDPP3T) as the active layer in organic solar cell. High external quantum efficiency (8.32%) and a fill factor (FF) of 0.76 are achieved under AM 1.5 illumination. The Voc of the tandem solar cells are almost equivalent to the sum of the sub-cells. The high performance of the device results from the complementary absorption spectra of two sub-cells. The SEM cross-sectional image of the device has been analysed and the distributions of the component elements can be clearly observed.

Recent Progress in Interconnection Layer for Hybrid Photovoltaic Tandems.

Hybrid tandem solar cells offer the benefits of low cost and full solar spectrum utilization. Among the hybrid tandem structures explored to date, the most popular ones have four (simple stacking design) or two (terminal/tunneling layer addition design) terminal electrodes. Although the latter design is more cost-effective than the former, its widespread application is hindered by the difficulty of preparing an interface between two solar cell materials. The oldest approach to the in-series bonding of two or more bandgap solar cells relies on the introduction of a tunneling layer in multijunction III-V solar cells, but it has some limitations, e.g., the related materials/technologies are applicable only to III-V and certain other solar cells. Thus, alternative methods of realizing junction contacts based on the use of novel materials are highly sought after. Here, the strategies used to realize high-performance tandem cells are described, focusing on interface control in terms of bonding two or more solar cells for tandem approaches. The presented information is expected to aid the establishment of ideal methods of connecting two or more solar cells to obtain the highest performance for different solar cell choices with minimized energy loss through the interface.

Nanostructural Investigation on GaAs//Indium Tin Oxide/Si Junctions for III-V-on-Si Hybrid Multijunction Cells

Hard X-ray photoemission spectroscopy (HAXPES) measurements and transmission electron microscopy (TEM) observations are performed on GaAs thin film//Indium tin oxide (ITO)/Si junctions fabricated by surface-activated bonding and selective wet etching. Both of the Ga-O/Ga-As ratio in the Ga 2p3/2 HAPES core spectrum (Fig. 1(a)) and As-O/As-Ga ratio in the As 2p3/2 HAXPES core spectrum (Fig. 1(b)) demonstrate that the GaAs layers are oxidized after annealing at 400 °C. This observation is consistent with the formations of a ~1-nm-thick intermediate layer in the cross-sectional TEM image of the junctions after the 400 °C annealing, as is shown in Figs. 2(a) and 2(b). It is found by using in-house X-ray photoelectron spectroscopy in combination with Ar+ bombardment that the oxide layers are formed at GaAs//ITO bonding interfaces after annealing at 200 °C or higher temperatures. The observation of the oxide layers corresponds with the onset of resistivity increase in GaAs//ITO/Si junctions due to the annealing [1]. These results suggest that annealing brings about the reaction between GaAs and ITO layers and hence the oxidation of GaAs layers, which causes the degradation of the electrical properties of GaAs//ITO/Si junctions. A fabrication process at lower temperatures is likely to be required so as to fully exploit the advantage of ITO as intermediate layers in III-V//Si hybrid tandem solar cells with lower series resistance.[1] Tomoya Hara, Tomoki Ogawa, Jianbo Liang, Kenji Araki, Takefumi Kamioka, and Naoteru Shigekawa, "Electrical properties of GaAs//indium tin oxide/Si junctions for III-V-on-Si hybrid multijunction cells", Jpn. J. Appl. Phys. 57, 08RD05 (2018). DOI: 10.7567/JJAP.57.08RD05 Figure 1

Monolithic Organic/Colloidal Quantum Dot Hybrid Tandem Solar Cells via Buffer Engineering.

Monolithically integrated hybrid tandem solar cells (TSCs) that combine solution-processed colloidal quantum dot (CQD) and organic molecules are a promising device architecture, able to complement the absorption across the visible to the infrared. However, the performance of organic/CQD hybrid TSCs has not yet surpassed that of single-junction CQD solar cells. Here, a strategic optical structure is devised to overcome the prior performance limit of hybrid TSCs by employing a multibuffer layer and a dual near-infrared (NIR) absorber. In particular, a multibuffer layer is introduced to solve the problem of the CQD solvent penetrating the underlying organic layer. In addition, the matching current of monolithic TSCs is significantly improved to 15.2 mA cm-2 by using a dual NIR organic absorber that complements the absorption of CQD. The hybrid TSCs reach a power conversion efficiency (PCE) of 13.7%, higher than that of the corresponding individual single-junction cells, representing the highest efficiency reported to date for CQD-based hybrid TSCs.

High‐Efficiency Solution‐Processed Two‐Terminal Hybrid Tandem Solar Cells Using Spectrally Matched Inorganic and Organic Photoactive Materials

AbstractAlthough the power conversion efficiency (PCE) of inorganic perovskite‐based solar cells (PSCs) is considerably less than that of organic‐inorganic hybrid PSCs due to their wider bandgap, inorganic perovskites are great candidates for the front cell in tandem devices. Herein, the low‐temperature solution‐processed two‐terminal hybrid tandem solar cell devices based on spectrally matched inorganic perovskite and organic bulk heterojunction (BHJ) are demonstrated. By matching optical properties of front and back cells using CsPbI2Br and PTB7‐Th:IEICO‐4F BHJ as the active materials, a remarkably enhanced stabilized PCE (18.04%) in the hybrid tandem device as compared to that of the single‐junction device (9.20% for CsPbI2Br and 10.45% for PTB7‐Th:IEICO‐4F) is achieved. Notably, the PCE of the hybrid tandem device is thus far the highest PCE among the reported tandem devices based on perovskite and organic material. Moreover, the long‐term stability of inorganic perovskite devices under humid conditions is improved in the hybrid tandem device due to the hydrophobicity of the PTB7‐Th:IEICO‐4F back cell. In addition, the potential promise of this type of hybrid tandem device is calculated, where a PCE of as much as ≈28% is possible by improving the external quantum efficiency and reducing energy loss in the sub‐cells.

Efficient monolithic perovskite/organic tandem solar cells and their efficiency potential

Abstract A high-performance monolithic perovskite/organic tandem solar cell based on the integration of a large bandgap CsPbI2Br inorganic perovskite front cell with a narrow bandgap PM6:Y6-based or PTB7-Th:O6T-4F-based bulk-heterojunction organic rear cell is demonstrated. Large bandgap inorganic perovskites are well suited candidates for the front cell due to their excellent optoelectronic properties and broad absorption for visible light, they also possess smaller voltage loss (Eloss) and higher external quantum efficiency (EQE) response when compare to their organic counterparts with approximate bandgap. Low bandgap organic solar cells offer potentially better stability and absorption tunability compared with the Sn-based perovskite counterparts, making them be good candidates for the rear cell of the tandem cells. As a result, the best power conversion efficiency (PCE) of the perovskite/organic tandem cell presented in this work reaches over 18%. In addition, based on the photovoltaic performance parameters (EQE, fill factor (FF), Eloss) that have already been achieved in state-of-the-art organic and perovskite solar cells, we further evaluate the potential PCE of the perovskite/organic tandem cells, showing a maximum calculated PCE of over 31% when the bandgaps of the subcells are optimized. This work paves the way for the development of hybrid tandem solar cells with promising performance.

Efficient Hybrid Tandem Solar Cells Based on Optical Reinforcement of Colloidal Quantum Dots with Organic Bulk Heterojunctions

AbstractWhile colloidal quantum dot photovoltaic devices (CQDPVs) can achieve a power conversion efficiency (PCE) of ≈12%, their insufficient optical absorption in the near‐infrared (NIR) regime impairs efficient utilization of the full spectrum of visible light. Here, high‐efficiency, solution‐processed, hybrid series, tandem photovoltaic devices are developed featuring CQDs and organic bulk heterojunction (BHJ) photoactive materials for front‐ and back‐cells, respectively. The organic BHJ back‐cell efficiently harvests the transmitted NIR photons from the CQD front‐cell, which reinforces the photon‐to‐current conversion at 350–1000 nm wavelengths. Optimizing the short‐circuit current density balance of each sub‐cell and creating a near ideal series connection using an intermediate layer achieve a PCE (12.82%) that is superior to that of each single‐junction device (11.17% and 11.02% for the CQD and organic BHJ device, respectively). Notably, the PCE of the hybrid tandem device is the highest among the reported CQDPVs, including single‐junction devices and tandem devices. The hybrid tandem device also exhibits almost negligible degradation after air storage for 3 months. This study suggests a potential route to improve the performance of CQDPVs by proper hybridization with NIR‐absorbing photoactive materials.

Optimization of device design for low cost and high efficiency planar monolithic perovskite/silicon tandem solar cells

Perovskite/silicon hybrid tandem solar cells are very close to commercialization owing to their low cost and relatively high efficiency compared to tandem cells based on III-V compound semiconductors. However, most hybrid tandem cell research is based on n-type heterojunction Si cells, which occupy only a small fraction of the total solar market. Here, we propose a new method for optimizing the design of low-cost and high-efficiency monolithic tandem cells based on p-type homojunction Si cells by realizing lossless current matching by simultaneously controlling the band gap energy and thickness of the perovskite film. In addition, systematic studies have been conducted to determine the optimal hole transport layer applicable to the tandem cell from the viewpoint of band alignment and process compatibility, in order to reduce the open-circuit voltage loss. Optimized tandem cells, which were fabricated with a 310 nm thick perovskite layer of (FAPbI3)0.8(MAPbBr3)0.2 and a hole transport layer of poly(triaryl amine), had a significantly increased efficiency of 21.19% compared to semi-transparent stand-alone perovskite (13.4%) and Si cells (12.8%). Our tandem cell represented the highest efficiency increment among all monolithic perovskite/Si tandem cells as well as the highest efficiency among monolithic perovskite/Si tandem cells based on p-type homojunction Si cells with Al back-surface fields. The design rules suggested in this study could also be applicable to different types of perovskite/Si tandem cells.

Hybrid Tandem Quantum Dot/Organic Solar Cells with Enhanced Photocurrent and Efficiency via Ink and Interlayer Engineering

Realization of colloidal quantum dot (CQD)/organic photovoltaic (OPV) tandem solar cells that integrate the strong infrared absorption of CQDs with large photovoltages of OPVs is an attractive option toward high-performing, low-cost thin-film solar cells. To date, monolithic hybrid tandem integration of CQD/OPV solar cells has been restricted due to the CQD ink’s catastrophic damage to the organic subcell, thus forcing the low-band-gap CQD to be used as a front cell. This suboptimal configuration limits the maximum achievable photocurrent in CQD/OPV hybrid tandem solar cells. In this work, we demonstrate hybrid tandem solar cells employing a low-band-gap CQD back cell on top of an organic front cell thanks to a modified CQD ink formulation and a robust interconnection layer (ICL), which together overcome the long-standing integration challenges for CQD and organic subcells. The resulting tandem architecture surpasses previously reported current densities by ∼20–25% and yields a state-of-the-art power conv...

Advanced light management techniques for two-terminal hybrid tandem solar cells

Multi-junction solar cells are considered for various applications, as they tackle various loss mechanisms for single junction solar cells. These losses include thermalization and non-absorption below the band gap. In this work, a tandem configuration comprising copper-indium-gallium-di-selenide (CIGS) and hydrogenated amorphous silicon (a-Si:H) absorber layers is studied. Two main challenges are addressed in this work. Firstly, the natural roughness of CIGS is unfavorable for monolithically growing a high quality a-Si:H top cell. Some sharp textures in the CIGS induce shunts in the a-Si:H top junction, limiting the electrical performance of such a configuration. To smoothen this interface, the possibility of mechanically polishing the intermediate i-ZnO layer has been explored. The second challenge that is addressed, is the significant current mismatch in these tandem architectures. To enhance absorption in the current-limiting top cell, the ZnO:Al front electrode was textured by means of wet-etching the entire tandem stack. We demonstrated that one can manipulate the morphology of the random textures by varying the growth conditions of the ZnO:Al, leading to better light management in these devices.

Towards maximizing the haze effect of electrodes for high efficiency hybrid tandem solar cell

In this study, we executed optical simulations to compute the optimum power conversion efficiency (PCE) of a-Si:H/organic photovoltaic (OPV) hybrid tandem solar cell. The maximum ideal short circuit current density (Jsc,max) of the tandem solar cell is initially obtained by optimizing the thickness of the active layer of the OPV subcell for varying thickness of the a-Si:H bottom subcell. To investigate the effect of Haze parameter on the ideal short-circuit current density (Jsc,ideal) of the solar cells, we have varied the haze ratio for the TCO electrode of the a-Si:H subcell in the tandem structure. The haze ratio was obtained for various root mean square (RMS) roughness of the TCO of the front cell. The effect of haze ratio on the Jsc,ideal on the tandem structured solar cell was studied, and the highest Jsc,ideal was obtained at a haze of 55.5% when the thickness of the OPV subcell was 150nm and that of the a-Si:H subcell was 500nm.

Low-bandgap conjugated polymers enabling solution-processable tandem solar cells

The technology of polymer-based organic photovoltaic (OPV) cells has made great progress in the past decade, with the power conversion efficiency increasing from just a few per cent to around 12%, and the stability increasing from hours to years. One of the important milestones in this progress has been the invention of infrared-absorbing low-bandgap polymers, which allows the OPV cells to form effective tandem structures for harvesting near-infrared energy from the solar spectrum. In this Review, we focus on the progress in low-bandgap conjugated polymers and several tandem OPV cells enabled by these low-bandgap polymers. Specifically, we cover polymer-based tandem solar cells; hybrid tandem solar cells combining polymers with hydrogenated amorphous silicon; and unconventional solar cells. For each of these technologies, we address the challenges and offer our perspectives for future development. Low-bandgap (<1.6 eV) polymers enable polymer solar cells to form effective tandem structures for harvesting near-infrared solar energy as well as reducing thermal loss. This Review summarizes recent progress and provides a perspective on various low-bandgap polymer-containing tandem solar cells; namely, pure polymer–polymer tandem, hybrid polymer–amorphous silicon tandem and unconventional perovskite–polymer tandem solar cells.

Hybrid tandem quantum dot/organic photovoltaic cells with complementary near infrared absorption.

Monolithically integrated hybrid tandem solar cells that effectively combine solution-processed colloidal quantum dot (CQD) and organic bulk heterojunction subcells to achieve tandem performance that surpasses the individual subcell efficiencies have not been demonstrated to date. In this work, we demonstrate hybrid tandem cells with a low bandgap PbS CQD subcell harvesting the visible and near-infrared photons and a polymer:fullerene-poly (diketopyrrolopyrrole-terthiophene) (PDPP3T):[6,6]-phenyl-C60-butyric acid methyl ester (PC61BM)-top cell absorbing effectively the red and near-infrared photons of the solar spectrum in a complementary fashion. The two subcells are connected in series via an interconnecting layer (ICL) composed of a metal oxide layer, a conjugated polyelectrolyte, and an ultrathin layer of Au. The ultrathin layer of Au forms nano-islands in the ICL, reducing the series resistance, increasing the shunt resistance, and enhancing the device fill-factor. The hybrid tandems reach a power conversion efficiency (PCE) of 7.9%, significantly higher than the PCE of the corresponding individual single cells, representing one of the highest efficiencies reported to date for hybrid tandem solar cells based on CQD and polymer subcells.

Hybrid Organic Tandem Solar Cell Comprising Small-Molecule Bottom and Polymer:Fullerene Top Subcells Fabricated by Thin-Film Transfer

Multilayer structures involving solution-deposited polymer films are difficult to fabricate, not allowing for unrestricted designs of polymer-based optoelectronic devices required for maximizing their performance. Here, we fabricate a hybrid organic tandem solar cell whose top and bottom subcells have polymer:fullerene and small molecules active layers, respectively, by a solvent-free process based on transferring the polymer:fullerene layer from an elastomeric stamp onto a vacuum-deposited bottom subcell. The interface between small-molecule and transferred polymer:fullerene layers is void-free at the nanoscale, allowing for efficient charge transport across the interface. Consequently, the transfer-fabricated tandem cell has an open-circuit voltage (VOC) almost identical to the sum of VOC values for the single-junction devices. The short-circuit current density (JSC) of the tandem cell is maximized by current matching achieved by varying the thickness of the small-molecule active layer in the bottom subcell, which is verified by numerical simulations. The optimized transfer-fabricated tandem cell, whose active layers are composed of poly[2,1,3-benzothiadiazole-4,7-diyl[4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b′]dithiophene-2,6-diyl]]:[6,6]-Phenyl-C71-butyric acid methyl ester and Di-[4-(N,N-di-p-tolyl-amino)-phenyl]cyclohexane:C70, has VOC = 1.46 V, JSC = 8.48 mA/cm2, a fill factor of 0.51, leading to the power-conversion efficiency of 6.26%, the highest among small molecule–polymer:fullerene hybrid tandem solar cells demonstrated so far.

Efficient Top-Illuminated Organic-Quantum Dots Hybrid Tandem Solar Cells with Complementary Absorption

Organic and quantum dots (QDs) semiconductors are promising to build low-cost hybrid tandem solar cells since they are both fully solution-processable, and have tunable bandgaps and absorption spectra. The challenges for high-performance organic-QDs tandem solar cells are to balance the photocurrent in subcells and construct an efficient charge-recombination layer (CRL) to maximize the efficiency of the whole tandem cell. In this work, we report a top illuminated organic-QDs hybrid tandem solar cell that employs an organic-based front subcell and a PbS QDs-based back subcell where the organic absorber complements the absorption deficiency of QDs film in the range of 650–900 nm. The hybrid tandem solar cell is monolithically integrated and electrically connected with a Spiro-MeOTAD/MoO3/Ag/PEIE CRL. A conversion efficiency of 7.4% is achieved for the hybrid tandem cells. The tandem solar cells exhibit an open-circuit voltage of 1.12 V, which is nearly the sum of the VOC of individual subcells, and a fill f...

A novel organic–inorganic hybrid tandem solar cell with inverted structure

A novel organic–inorganic hybrid tandem solar cell with inverted structure is proposed. This efficient double-junction hybrid tandem solar cell consists of a single-junction hydrogenated amorphous silicon (a-Si:H) subcell with n-i-p structure as front cell and a P3HT:PCBM organic subcell with inverted structure as back cell. In order to optimize the hybrid tandem cell, we have performed a simulation based on transfer matrix method. We have compared the characteristics of this novel structure with a conventional structure. As a result, a power conversion efficiency (PCE) of 6.1 and 24% improvement compared to the conventional hybrid tandem cell was achieved. We also discuss the high potential of this novel structure for realizing high-stability organic–inorganic hybrid photovoltaic devices.