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This research paper examines the execution of ultra-thin solar cells made from chalcopyrite copper indium gallium diselenide (CIGS). The study presents a new CIGS heterojunction solar cell structure, which includes a Cd-free tungsten disulfide (WS 2) buffer layer and poly (3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT: PSS) passivation layer. The performance of the solar cell is raised by a back surface field (BSF). A highly recombining rear surface is kept away from minority carriers by a field created by further strong doping at the back. The structure is Ni/PEDOT:PSS/CIGS/WS 2 /ZnO/Al and has been estimated numerically using the Opto-electrical stimulation of semiconductor layers simulator SCAPS-1D. A high efficiency with a Back surface passivated layer of 25.70 % with V oc of 0.81 V, J sc of 39.33 mA/cm2, and FF of 79.89 % and without passivated layer efficiency of 17.58 % with V oc of 0.73 V, J sc of 32.18 mA/cm2, and FF of 74.78 % is found for the intended CIGS-based solar cell with WS 2 buffer. The interface between CIGS and WS 2 forms a band structure that resembles spikes. This structure is crucial in enhancing the outputs by reducing carrier recombination. The optimal thicknesses for the buffer and CIGS absorber layers are 0.02 μm and 0.2 μm, respectively. These findings help reduce the cost per watt of the solar cell. Fabrication at a mass production scale, minimizing the thickness will have a significant impact on reducing cost. • A novel heterojunction Ni/PEDOT:PSS/CIGS/WS 2 /ZnO/Al solar cell has been designed. • Reducing the thickness of the CIGS absorber layer means a reduction in the cost per watt of the solar cell. • For the first time, an Ultra-thin (200 nm) CIGS solar cell with back surface passivation got an efficiency of 25.70 % with V oc of 0.81 V, J sc of 39.33 mA/cm2, and FF of 79.89 % evaluated. • Improvement of the performance of CIGS solar cells using back surface passivation that minimizes the recombination losses. • Cd-free WS 2 buffer layer with a CIGS absorber reduces carrier recombination and enhances PV outputs. [ABSTRACT FROM AUTHOR]

The quest for material‐efficient Cu(In,Ga)Se2 (CIGS) solar cells encourages the development of ultra‐thin absorbers. Their use reduces material consumption and energy usage during production by increasing the throughput. Thereby, both the bill of materials as well as the energy and capital costs are reduced. However, because thin absorbers are prone to increase back contact recombination, back surface passivation schemes are necessary to reach a similar or higher conversion efficiency than for absorbers with conventional thickness. Here, we investigate nanostructured hafnium oxide (HfO2) rear passivation layers for ultra‐thin CIGS solar cells. We fabricate regular arrays of point contacts with 200 nm diameter through HfO2 layers with thicknesses between 7 and 40 nm using electron beam lithography and reactive ion etching. The current–voltage curves of solar cells with a 500 nm thick CIGS absorber layer and the nanostructured passivation layer show improved performance concerning Voc and Jsc compared to non‐passivated reference devices. Furthermore, external quantum efficiency and optical reflection confirm an effective passivation behavior, with an average efficiency increase of up to 1.2% for the cells with the 40 nm thick HfO2 layer. In addition, simulation work shows that even 40 nm thick HfO2 passivation layers have only a minimal effect on the optical properties of ultra‐thin CIGS solar cells, and hence, the photocurrent increase verified experimentally stems from electrical improvements caused by the HfO2 layer passivation effect. We also investigate the impact of ultra‐thin (0.3, 0.6, 1.3, and 2.5 nm) non‐patterned HfO2 passivation layers on the same type of solar cells. However, these results showed no improvement in solar cell performance, despite an increase in the current density with layer thickness. [ABSTRACT FROM AUTHOR]

Cadmium Telluride thin film solar cell is very suitable for building integrated photovoltaics due to its high efficiency and excellent stability. To further reduce the production costs, relieve the scarcity of Tellurium, and apply in building integrated photovoltaics, ultra-thin CdTe photovoltaic technology has been developed. Some study have discussed the research progress of ultra-thin solar cells in terms of silicon and copper indium gallium selenide solar cells, but there are few review papers from the aspect of CdTe solar cells. This review focuses on the ultra-thin CdTe solar cell for the first time and provides a comprehensive and systematic summary. Firstly, the structure of this device is described, and the history of its development is reviewed. Secondly, the advantages and disadvantages of different methods are discussed, and the corresponding solutions are given. Thirdly, the factors limiting device efficiency are analyzed and future directions are suggested. Lastly, the application of ultra-thin device in semi-transparent devices is presented and the challenges are summarized. By reviewing a wide range of materials, we aim to provide valuable insights into the development of ultra-thin cadmium telluride solar cells and to promote its application in building integrated photovoltaics, which is of great importance in reducing carbon emissions to achieve sustainable development. [Display omitted] • This study makes a comprehensive and systematic summary of the development history of ultra-thin CdTe solar cell. • It also analyzes the factors limiting the device efficiency and discusses how to improve the device V oc and J sc. • The future trends and challenges are discussed. • Outlooks the development prospect of ultra-thin semi-transparent CdTe solar cells in BIPV and tandem cell. [ABSTRACT FROM AUTHOR]

Ultra‐thin photovoltaics enable lightweight flexible form factors, suitable for emerging terrestrial applications such as electric vehicle integration. These devices also exhibit intrinsic radiation tolerance and increased specific power and so are uniquely enabling for space power applications, offering longer missions in hostile environments and reduced launch costs. In this work, a GaAs solar cell with an 80‐nm absorber is developed with short circuit current exceeding the single pass limit. Integrated light management is employed to compensate for increased photon transmission inherent to ultra‐thin absorbers, and efficiency enhancement of 68% over a planar on‐wafer equivalent is demonstrated. This is achieved using a wafer‐scale technique, displacement Talbot lithography, to fabricate a rear surface nanophotonic grating. Optical simulations definitively confirm Fabry‐Perot and waveguide mode contributions to the observed increase in absorption and also demonstrate a pathway to short circuit current of 26 mA/cm2, well in excess of the double pass limit. [ABSTRACT FROM AUTHOR]

For the commercialization of perovskite solar cells (PSCs), it is more appealing to develop high‐performance simplified PSCs where perovskite films are just sandwiched between the back and front electrodes, in order to simplify the fabrication process and to reduce the cost. However, to date, this kind of devices shows rather low performance, and there are few researches on this subject. Herein, we report on a kind of compact PSCs (CPSCs) that are free of independent charge transport layers (CTLs). The devices are realized by the use of organic monolayer‐modified effective electrodes, along with the use of [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM)‐assisted anti‐solvent technique to obtain ultra‐thin (~10 nm) PCBM‐embedded perovskite films. Compared to control devices, CPSCs achieve a promising champion power conversion efficiency of 19.6% with largely reduced hysteresis. Moreover, the unencapsulated CPSC shows good stability under ambient atmosphere, with only 10% efficiency loss after 60 days' storage. This work indicates that, by delicate design, CPSCs with smaller materials consumption in device architecture can perform competitively as conventional PSCs. Further reduction in the actual usage of costly CTL materials can be expected upon our CPSCs by developing more facile and economic methods to prepare ultra‐thin CTLs. [ABSTRACT FROM AUTHOR]

The demand for cheaper and more efficient solar cells is the main reason behind the ongoing research on ultra-thin solar cells. In this research work, the electric field generated by the surface plasmons effects has been used to design an ultra-thin silicon solar cell. The main idea of this work is the use of paired nanoparticles with both the same and different radiuses. At first, a cell with one nanoparticle in embedded and non-embedded forms is designed and photocurrents of 11.52 and 20.87 mA/cm2 are obtained, respectively. In the case of paired nanoparticles, the photocurrents of 11.9 and 21.68 mA/cm2 are obtained for embedded and non-embedded cases, respectively. These values are 11.89 and 21.84 mA/cm2 for paired nanoparticles with different radiuses. Our simulated results show that embedded nanoparticles significantly improve the photocurrent of an ultra-thin silicon solar cell. This approach and obtained results are applicable to various cell, thicknesses, and shapes of nanoparticles. [ABSTRACT FROM AUTHOR]

In this work, we evaluate the effect of NaF layers on the properties of Al 2 O 3 and HfO 2 rear contact passivation layers in ultra-thin Cu(In,Ga)Se 2 solar cells. The 6 nm thin passivation layers were deposited by atomic layer deposition and neither intentionally opened nor nano-patterned in any extra-fabrication step. NaF layers, 7.5 or 15 nm thin, were deposited as precursors prior to CIGS absorber co-evaporation. The 215 nm thick absorbers were co-evaporated with constant evaporation rates for all elements. Directly thereafter, a 70 nm thick cadmium sulfide layer was deposited. Photoluminescence measurements indicate a strongly reduced recombination at the rear contact for all passivated samples compared to an unpassivated reference. Although the sample with Al 2 O 3 passivation and a 15 nm NaF precursor layer luminesces by far the least of the passivated samples, solar cells made from this sample show the highest efficiency (8.6% compared with 5.6% for the reference with no passivation). The current-voltage curves of the solar cells fabricated from the sample with 7.5 nm NaF on top of the Al 2 O 3 layer and both samples with HfO 2 exhibit blocking behavior to various degrees, but a high photoluminescence response. We conclude that NaF precursor layers increase conduction through the Al 2 O 3 layer, but also reduce its effectiveness as a passivation layer. In contrast, conduction through the HfO 2 passivation layers seem to not be influenced by NaF precursor layers, and thus requires nano-patterning or thinning for conduction. • Large photoluminescence signal due to rear contact passivation with hafnia and alumina • Negligible current blocking if sufficiently thick NaF precursor used on alumina layers • Thick NaF layers decrease the passivation effectiveness of alumina layers. • NaF precursor layers do not make hafnia layer conductive. • NaF precursor layers do not decrease the passivation effectiveness of hafnia layers. [ABSTRACT FROM AUTHOR]

We report on the fabrication of a 5.2% efficiency Cu 2 ZnSnS 4 (CZTS) solar cell made by pulsed laser deposition (PLD) featuring an ultra-thin absorber layer (less than 450 nm). Solutions to the issues of reproducibility and micro-particulate ejection often encountered with PLD are proposed. At the optimal laser fluence, amorphous CZTS precursors with optimal stoichiometry for solar cells are deposited from a single target. Such precursors do not result in detectable segregation of secondary phases after the subsequent annealing step. In the analysis of the solar cell device, we focus on the effects of the finite thickness of the absorber layer. Depletion region width, carrier diffusion length, and optical losses due to incomplete light absorption and back contact reflection are quantified. We conclude that material- and junction quality is comparable to that of thicker state-of-the-art CZTS devices, even though the efficiency is lower due to optical losses. [ABSTRACT FROM AUTHOR]

A new non-conjugated polymer (PVCz-OMeDAD) with good solution processability was developed to serve as an efficient dopant-free hole-transporting material (HTM) for perovskite solar cells (PSCs). PVCz-OMeDAD was simply prepared by the free-radical polymerization of vinyl monomers, which were synthesized from low-cost raw materials through three high-yield synthesis steps. The combination of the flexible non-conjugated polyvinyl main chain and hole-transporting methoxydiphenylamine-substituted carbazole side chains endowed PVCz-OMeDAD with excellent film-forming ability, a suitable energy level, and high hole mobility. As a result, by using an ultra-thin (≈30 nm) PVCz-OMeDAD film as cost-effective dopant-free polymer HTM, the conventional n-i-p-type PSCs demonstrated a power conversion efficiency (PCE) up to 16.09 %, suggesting the great potential of the polymer film for future low-cost, large-scale, flexible PSCs applications. [ABSTRACT FROM AUTHOR]

The present contribution reports on the performances of ultra thin chalcopyrite Cu (In,Ga) Se (CIGS) solar cells. An alternative ZnO/CdS/CIGS/Si structure has been proposed using solar cell capacitance simulator (SCAPS). The main idea behind this analysis is the improvement of the device efficiency using materials cheaper than conventional CIGS. For that purpose, a 1 μm of a new layer p-Si has been added. Various thicknesses of CIGS absorber layer ranging from 0.1 to 1 μm have been used. Our findings showed that the increase of the absorber layer thickness leads to the improvement of the performance of the new CIGS solar cells. It was found that the best structure must have a window layer ZnO, a buffer layer (CdS), an absorbent layer (CIGS) and a Si layer with thicknesses of 0.02, 0.05, 1 and 1 μm, respectively. Cells with these features give conversion efficiency of 21.3%. The present results showed that the new ultra thin CIGS solar cells structure has performance parameters that are comparable to those of the conventional ones with reduced cost. [ABSTRACT FROM AUTHOR]

In this paper, we proposed a broadband and ultra-thin metamaterial absorber in the visible region. The absorber is composed of three layers, and the most remarkable difference is that the split ring resonators (SRR) made of metal stannum are encrusted in the indium antimonide (InSb) plane on the top layer. Numerical results reveal that a broadband absorption spectrum above 90% can be realized from 353.9 THz to 613.2 THz due to the coupling effect between the material of stannum and InSb. The metamaterial absorber is ultra-thin, having the total thickness of 56 nm, i.e. less than λ/10 with respect to the center frequency of the absorption band more than 90%. In addition, the impedance matching theory, surface current distributions, E-field and H-field are investigated to explain the physical mechanism of the absorption. The sensing applications are discussed and the simulated results show that the proposed absorber operates well with a good efficiency. Moreover, the visible absorber has potential applications in the aspects of solar energy harvest, integrated photodetectors and so on. [ABSTRACT FROM AUTHOR]

The superstrate configuration of Cu(In,Ga)Se 2 (CIGS) photovoltaic devices exhibits the potential for improved light harvesting compared to the standard substrate configuration. Due to the limited power conversion efficiency of superstrate devices caused by the poor hetero-interface between the p -type CIGS and the n -type component, these advantages have not been fully considered so far. This work shows that the superstrate configuration can significantly improve the light management within CIGS devices. Experimentally, it is shown that the electric and optical properties of ZnO window layer strongly improve during the CIGS deposition, allowing the use of structured ZnO layers for efficient light-trapping. A highly reflective and scattering back contact is realized by using the high work function material MoO 3− x for the hole-transport layer in combination with a low work function Ag metal layer. Combined with the unique Ga gradient achievable in the superstrate configuration, simulation results show that a strong reduction of the CIGS layer thickness is possible while increasing the power conversion efficiency. This proof of concept highlights the appeal of the superstrate configuration for the future of cost-effective CIGS solar cell production. [ABSTRACT FROM AUTHOR]

To investigate the process temperature on the growth of ultra-thin (≤500 nm) Cu(In,Ga)Se 2 (CIGSe) absorbers and the corresponding performance of solar cells, the process temperature was set to 610 °C and 440 °C, respectively. It was found that the low process temperature (440 °C) could reduce the inter-diffusion of Ga–In and thus result in a higher back [Ga]/([Ga]+[In]) ([Ga]/[III]) grading than at the temperature of 610 °C. The higher back [Ga]/[III] grading at 440 °C was evidenced to both electrically and optically contribute to the efficiency enhancement of the solar cells in contrast to the lower back [Ga]/[III] grading at 610 °C. It was also implied that the high back [Ga]/[III] grading was beneficial to the collection of carriers generated from the back-reflected light. [ABSTRACT FROM AUTHOR]

In this study, a new CdTe solar cell structure was proposed, where Zinc Cadmium Sulfide (ZnxCd1-xS) was used as window layer with an added advantage of variable bandgap. By varying the composition of the zinc content, the bandgap was varied between 2.42- 3.7 eV, thereby increasing the cell's performance in the lower wavelength region, resulting in higher efficiency. The CdTe absorber layer was decreased to the extreme limit of 1 μm and at this thickness the proposed cell has shown acceptable range of efficiency. Moreover, the thickness of ZnxCd1-xS window layer was reduced to 60 nm with a suitable buffer layer either with zinc oxide (ZnO) or zinc stannate (Zn2SnO4) to prevent forward leakage current of ultra thin ZnxCd1-xS layer. The Analysis of Microelectronics and Photonics Structures (AMPS) 1-D software was used to simulate and analyze the cell's performance (efficiency, FF, Voc, Jsc, temperature stability) with different variables. The results have shown that an efficiency of up to 19.5% is feasible of cost-effective ultra-thin ZnxCd1-xS/CdTe solar cell structure with 1 μm of CdTe, 60 nm of ZnxCd1-xS and 100 nm of ZnO or Zn2SO4 buffer layers. The cells stability with temperature and other material properties was also studied and analyzed. [ABSTRACT FROM AUTHOR]