Quasiepitaxy Strategy for Efficient Full‐Inorganic Sb2S3 Solar Cells

Antimony sulfide (Sb₂S₃) as a wide‐bandgap, nontoxic, and stable photovoltaic material reveals great potential for the uppermost cells in Si‐based tandem cell stacks. Sb₂S₃ solar cells with a compatible process, acceptable cost, and high efficiency therefore become the mandatory prerequisites to match silicon bottom cells. The performance of vacuum processed Sb₂S₃ device is pinned by bulk and interfacial recombination. Herein, a thermally treated TiO₂ buffer layer induces quasiepitaxial growth of vertical orientation Sb₂S₃ absorber overcoming interface defects and absorber transport loss. Such novel growth could pronouncedly improve the open‐circuit voltage (V_oc) due to the superior interface quality and intraribbon transport. The epitaxial rough Sb₂S₃ surface shows a texturized‐like morphology. It is optimized by tuning the grain sizes to form strong light trapping effect, which further enhances the short‐circuit current density (J_sc) with a 16% improvement. The final optimal device with high stability obtains a power conversion efficiency of 5.4%, which is the best efficiency for full‐inorganic Sb₂S₃ solar cells. The present developed quasiepitaxy strategy supports a superior interface, vertical orientation, and surface light trapping effect, which provides a new perspective for efficient noncubic material thin film solar cells.     

Enhanced Sb2Se3 solar cell performance through theory‐guided defect control

Defects present in the absorber layer largely dictate photovoltaic device performance. Recently, a binary photovoltaic material, Sb₂Se₃, has drawn much attention due to its low‐cost and nontoxic constituents and rapid performance promotion. So far, however, the intrinsic defects of Sb₂Se₃ remain elusive. Here, through a combined theoretical and experimental investigation, we revealed that shallow acceptors, Se_Sb antisites, are the dominant defects in Sb₂Se₃ produced in an Se‐rich environment, where deep donors, Sb_Se and V_Se, dominate in Sb₂Se₃ produced in an Se‐poor environment. We further constructed a superstrate CdS/Sb₂Se₃ thin‐film solar cell achieving 5.76% efficiency through in situ Se compensation during Sb₂Se₃ evaporation and through careful optimization of absorber layer thickness. The understanding of intrinsic defects in Sb₂Se₃ film and the demonstrated success of in situ Se compensation strategy pave the way for further efficiency improvement of this very promising photovoltaic technology. Copyright © 2017 John Wiley & Sons, Ltd.     

Flexible Substrate-Structured Sb2S3 Solar Cells with Back Interface Selenization

Antimony sulfide (Sb₂S₃) with a 1D molecular structure has strong bending characteristics, showing great application potential in flexible devices. Herein, the flexible substrate-structured Sb₂S₃ solar cells is developed and improve device performances by the back interface selenization. The high-quality Sb₂S₃ film with an optimal thickness of 1.8 µm, ensuring efficient spectra utilization, is deposited on flexible Mo foils by the rapid thermal evaporation technique. To solve the issues of back interfacial recombination and charge transport, the 20 nm MoSe₂ layer between Sb₂S₃ film and Mo foil is fabricated by substrate selenization in the tube furnace. Further investigations indicate that the MoSe₂ layer improves the interfacial energy band alignments and induces the [hk1] orientation of Sb₂S₃ film, thereby passivating defects and enhancing the carrier transport capacity. The flexible solar cell in the structure of Mo foil/MoSe₂/Sb₂S₃/CdS/ITO/Ag, exhibiting good flexibility to stand thousands of bending, achieves an efficiency of 3.75%, which is the highest for Sb₂S₃ devices in substrate configuration. The presented flexible structure and back interfacial selenization study will provide new prospects for inorganic Sb₂S₃ thin film solar cells.     

In Situ Growth of [hk1]‐Oriented Sb2S3 for Solution‐Processed Planar Heterojunction Solar Cell with 6.4% Efficiency

Binary compound antimony sulfide (Sb₂S₃) with its nontoxic and earth‐abundant constituents, is a promising light‐harvesting material for stable and high efficiency thin film photovoltaics. The intrinsic quasi‐1D (Q1D) crystal structure of Sb₂S₃ is known to transfer photogenerated carriers rapidly along the [hk1] orientation. However, producing Sb₂S₃ devices with precise control of [hk1] orientation is challenging and unfavorable crystal orientations of Sb₂S₃ result in severe interface and bulk recombination losses. Herein, in situ vertical growth of Sb₂S₃ on top of ultrathin TiO₂/CdS as the electron transport layer (ETL) by a solution method is demonstrated. The planar heterojunction solar cell using [hk1]‐oriented Sb₂S₃ achieves a power conversion efficiency of 6.4%, performing at almost 20% higher than devices based on a [hk0]‐oriented absorber. This work opens up new prospects for pursuing high‐performance Sb₂S₃ thin film solar cells by tailoring the crystal orientation.     

Highly Improved Sb2S3 Sensitized‐Inorganic–Organic Heterojunction Solar Cells and Quantification of Traps by Deep‐Level Transient Spectroscopy

The light‐harvesting Sb₂S₃ surface on mesoporous‐TiO₂ in inorganic–organic heterojunction solar cells is sulfurized with thioacetamide (TA). The photovoltaic performances are compared before and after TA treatment, and the state of the Sb₂S₃ is investigated by X‐ray diffraction, X‐ray photoelectron spectroscopy, and deep‐level transient spectroscopy (DLTS). Although there are no differences in crystallinity and composition, the TA‐treated solar cells exhibit significantly enhanced performance compared to pristine Sb₂S₃‐sensitized solar cells. From DLTS analysis, the performance enhancement is mainly attributed to the extinction of trap sites, which are present at a density of (2–5) × 10¹⁴ cm^?3 in Sb₂S₃, by TA treatment. Through such a simple treatment, the cell records an overall power conversion efficiency (PCE) of 7.5% through a metal mask under simulated illumination (AM 1.5G, 100 mW cm^–2) with a very high open circuit voltage of 711.0 mV. This PCE is, thus far, the highest reported for fully solid‐state chalcogenide‐sensitized solar cells.     

High‐Performance N‐type Mg3Sb2 towards Thermoelectric Application near Room Temperature

Se‐doped Mg_3.2Sb_1.5Bi_0.5‐based thermoelectric materials are revisited in this study. An increased ZT value ≈ 1.4 at about 723 K is obtained in Mg_3.2Sb_1.5Bi_0.49Se_0.01 with optimized carrier concentration ≈ 1.9 × 10¹⁹ cm^?3. Based on this composition, Co and Mn are incorporated for the manipulation of the carrier scattering mechanism, which are beneficial to the dramatically enhanced electrical conductivity and power factor around room temperature range. Combined with the lowered lattice thermal conductivity due to the introduction of effective phonon scattering centers in Se&Mn‐codoped sample, a highest room temperature ZT value ≈ 0.63 and a peak ZT value ≈ 1.70 at 623 K are achieved for Mg_3.15Mn_0.05Sb_1.5Bi_0.49Se_0.01, leading to a high average ZT ≈ 1.33 from 323 to 673 K. In particular, a remarkable average ZT ≈ 1.18 between the temperature of 323 and 523 K is achieved, suggesting the competitive substitution for the commercialized n‐type Bi₂Te₃‐based thermoelectric materials.     

Wide Bandgap Sb2S3 Solar Cells

The wide bandgap Sb₂S₃ is considered to be one of the most promising absorber layers in single-junction solar cells and a suitable top-cell candidate for multi-junction (tandem) solar cells. However, compared to mature thin-film technologies, Sb₂S₃ based thin-film solar cells are still lagging behind in the power conversion efficiency race, and the highest of just 7.5% has been achieved to date in a sensitized single-junction structure. Furthermore, to break single junction solar cell based Shockley–Queisser (S–Q) limits, tandem devices with wide bandgap top-cells and low bandgap bottom-cells hold a high potential for efficient light conversion. Though matured and desirable bottom-cell candidates like silicon (Si) are available, the corresponding mature wide bandgap top-cell candidates are still lacking. Hence, a literature review based on Sb₂S₃ solar cells is urgently warranted. In this review, the progress and present status of Sb₂S₃ solar cells are summarized. An emphasis is placed mainly on the improvement of absorber quality and device performance. Moreover, the low-performance causes and possible overcoming mechanisms are also explained. Last but not least, the potential and feasibility of Sb₂S₃ in tandem devices are vividly discussed. In the end, several strategies and perspectives for future research are outlined.     

Vapor Transport Deposition of Highly Efficient Sb2(S,Se)3 Solar Cells via Controllable Orientation Growth

The vapor transport deposition of quasi-one-dimensional antimony selenosulfide (Sb₂(S,Se)₃) has recently attracted increasing research interest for the inexpensive, high-throughput production of thin film photovoltaic devices. Further improvements in Sb₂(S,Se)₃ solar cell performance urgently require the identification of processing strategies to control the orientation, however the growth mechanism of high quality absorbers is still not completely clear. Herein, a facile and general vapor transport deposition approach to precisely control the growth of large-grained dense Sb₂(S,Se)₃ films with good crystallization and preferred orientation via the source vapor speed is utilized. It is found that defect activation energy rather than the defect concentration plays a decisive role in the Sb₂(S,Se)₃ photovoltaic performance. Admittance spectroscopy analysis is used to obtain efficient Sb₂(S,Se)₃ solar cells. By employing dual-source coordinations to optimize the absorber layer a power conversion efficiency of 8.17% is obtained which is the highest efficiency for Sb₂(S,Se)₃ solar cells fabricated by vapor transport technology. This study suggests that there are other opportunities for gaining deeper a understanding of the defect physics and carrier recombination mechanisms in other highly oriented low-dimensional materials to achieve improved device performance.     

Encapsulating Eu3+ complex doped layers to improve Si‐based solar cell efficiency

This paper reports the electrical characterization of commercially available crystalline silicon solar cells encapsulated with poly‐vinylacetate doped with different Eu³⁺ organic complexes. The inclusion of these complexes in the encapsulating matrix allows down‐shifting of the solar spectrum components below 420 nm toward the maximum quantum efficiency of the solar cells. This effect has been proven under Air Mass 1·5 conditions (simulating terrestrial applications) where an increase of the total power delivered by the encapsulated cells has been observed. Moreover, this enhancement has been obtained using very low percentage by weight of organolanthanide dopants, allowing a reduction in the Watt peak price. At higher concentrations a strong quenching of the energy transfer from the organic antenna to the lanthanide ion has been observed. Copyright © 2009 John Wiley & Sons, Ltd.     

Thin‐film Cu(In,Ga)(Se,S)2‐based solar cell with (Cd,Zn)S buffer layer and Zn1−xMgxO window layer

(Cd,Zn)S buffer layer and Zn_1−x Mg_x O window layer were investigated to replace the traditional CdS buffer layer and ZnO window layer in Cu(In,Ga)(Se,S)₂ (CIGSSe)‐based solar cell. (Cd,Zn)S with band‐gap energy (E _g) of approximately 2.6 eV was prepared by chemical bath deposition, and Zn_1−x Mg_x O films with different [Mg]/([Mg] + [Zn]) ratios, x , were deposited by radio frequency magnetron co‐sputtering of ZnO and MgO. The estimated optical E _g of Zn_1−x Mg_x O films is linearly enhanced from 3.3 eV for pure ZnO (x  = 0) to 4.1 eV for Zn_0.6Mg_0.4O (x  = 0.4). The quality of the Zn_1−x Mg_x O films, implied by Urbach energy, is severely deteriorated when x is above 0.211. Moreover, the temperature‐dependent current density‐voltage characteristics of the CIGSSe solar cells were conducted for the investigation of the heterointerface recombination mechanism. The external quantum efficiency of the CIGSSe solar cell with the (Cd,Zn)S buffer layer/Zn_1−x Mg_x O window layer is improved in the wavelength range of 320–520 nm. Therefore, a gain in short‐circuit current density up to about 5.7% was obtained, which is higher conversion efficiency of up to around 5.4% relative as compared with the solar cell with the traditional CdS buffer layer/ZnO window layer. The peak efficiency of 19.6% was demonstrated in CIGSSe solar cell with (Cd,Zn)S buffer layer and Zn_1−x Mg_x O window layer, where x is optimized at 0.211. Copyright © 2017 John Wiley & Sons, Ltd.     

Device characteristics of a 10.1% hydrazine‐processed Cu2ZnSn(Se,S)4 solar cell

A power conversion efficiency record of 10.1% was achieved for kesterite absorbers, using a Cu₂ZnSn(Se,S)₄ thin‐film solar cell made by hydrazine‐based solution processing. Key device characteristics were compiled, including light/dark J–V, quantum efficiency, temperature dependence of V_oc and series resistance, photoluminescence, and capacitance spectroscopy, providing important insight into how the devices compare with high‐performance Cu(In,Ga)Se₂. The record kesterite device was shown to be primarily limited by interface recombination, minority carrier lifetime, and series resistance. The new level of device performance points to the significant promise of the kesterites as an emerging and commercially interesting thin‐film technology. Copyright © 2011 John Wiley & Sons, Ltd.     

Sb2S3/TiO2纳米管异质结阵列的制备和光电性能

结合水热法和阳极氧化法合成了Sb2S3/TiO2纳米管异质结阵列,采用场发射扫描电子显微镜、X射线衍射谱表征了异质结阵列的形貌和晶体结构.暗态下的电流-电压曲线表明Sb2S3/TiO2纳米管异质结阵列具有整流效应.相比于纯的TiO2纳米管阵列,Sb2S3/TiO2纳米管异质结阵列的光电性能有了显著地提升:在AM1.5标准光强作用下,光电转换效率从0.07％增长到0.40％,表面光电压响应范围从紫外光区拓宽至可见光区.结合表面光电压谱和相位谱,分析了Sb2S3/TiO2纳米管异质结阵列中光生载流子的分离和传输性能.     

Effect of low segregation coefficient on Ga‐doped multicrystalline silicon solar cell performance

High‐quality Ga‐doped ingots are grown in different casting furnaces at optimized growth parameters; 3·5 kg ingots exhibit normal distribution of diffusion lengths along their height with very high diffusion lengths at the center of the ingot. Effective lifetimes as high as 1·1 ms are realized in 10 Ω cm Ga‐doped wafers after proper P‐diffusion and hydrogen passivation. Average effective lifetimes above 400 µs are also realized after P‐diffusion and hydrogen passivation for Ga‐doped wafers cut from 75 kg ingot where the response to P‐diffusion and hydrogen passivation is pronounced. High effective lifetimes are realized over the whole ingot with minimum values of 20 µs at the top of the ingot, indicating the possible use of about 85% of the ingot for solar cell production. Conversion efficiencies above 15·5% were realized in utilizing more than 80% of the ingot. High efficiencies of about 16% were realized in wafers with resistivities higher than 5 Ω cm p ‐type multicrystalline silicon wafers. Copyright © 2005 John Wiley & Sons, Ltd.     

High‐efficiency black silicon interdigitated back contacted solar cells on p‐type and n‐type c‐Si substrates

This work demonstrates the high potential of Al₂O₃ passivated black silicon in high‐efficiency interdigitated back contacted (IBC) solar cells by reducing surface reflectance without jeopardizing surface passivation. Very low reflectance values, below 0.7% in the 300–1000 nm wavelength range, together with striking surface recombination velocities values of 17 and 5 cm/s on p‐type and n‐type crystalline silicon substrates, respectively, are reached. The simultaneous fulfillment of requirements, low reflectance and low surface recombination, paves the way for the fabrication of high‐efficiency IBC Si solar cells using black silicon at their front surface. Outstanding photovoltaic efficiencies over 22% have been achieved both in p‐type and n‐type 9‐cm² cells. 3D simulations suggest that efficiencies of up to 24% can be obtained in the future with minor modifications in the baseline fabrication process. Copyright © 2015 John Wiley & Sons, Ltd.     

Direct Polarimetric Image Sensor and Wide Spectral Response Based on Quasi-1D Sb2S3 Nanowire

Polarized photodetectors with wide spectral detection and ultra-fast photoresponses based on anisotropic semiconductors have potential applications in military and civilian fields and have been widely studied in recent years. The dual advantages of low-symmetry crystal structure and special electronic band-structure make Sb₂S₃ the perfect choice for polarized photodetection. In this work, the optical, vibrational, and optoelectronic anisotropy of the high-quality orthorhombic Sb₂S₃ nanowires are systematically investigated by experimental and theoretical studies. The metal-semiconductor-metal photodetectors based on a single Sb₂S₃ nanowire exhibit good polarization sensitivity in a broadband range from ultraviolet to near-infrared (360 to 1550 nm) and the obtained maximum dichroic ratio is 2.54 at 638 nm. The polarization-sensitive photocurrent mapping results show that the photocurrent is mainly derived from the Schottky junction at the interface between Au and Sb₂S₃. The effective separation of the photo-generated carriers near the Schottky junction gives a photodetector response time of 470 µs. The direct polarimetric imaging demonstrates that the gray value of the image obtained by the imaging system is sensitive to the object's polarized direction. This natural sensitivity of the Sb₂S₃-based photodetector to polarized objects makes it possible to image polarized objects directly as an image sensor.     

Aluminum‐doped Zn1 − xMgxO as transparent conductive oxide of Cu(In,Ga)(S,Se)2‐based solar cell for minimizing surface carrier recombination

A 19.5%‐efficient Cu(In,Ga)(S,Se)₂ (CIGSSe)‐based solar cell is obtained by replacing traditional CdS/ZnO buffer layers with Cd_0.75Zn_0.25S/Zn_0.79Mg_0.21O buffer layers for increasing short‐circuit current density because band‐gap energies of Cd_0.75Zn_0.25S and Zn_0.79Mg_0.21O are wider than those of CdS and ZnO, respectively. This yields the increase in external quantum efficiency in a short wavelength range of approximately 320 to 550 nm. Moreover, difference of conduction band minimum (E _C) between Zn_1 − x Mg_x O:Al (transparent conductive oxide, TCO) layer and CIGSSe absorber is optimized by varying [Mg]/([Mg] + [Zn]), x . It is revealed that Zn_1 − x Mg_x O:Al films with [Mg]/([Mg] + [Zn]) in a range of 0.10 to 0.12, enhancing E _g from 3.72 to 3.76 eV, are appropriate as TCO because of their enhanced mobility and decreased carrier density. Addition of 12% Mg into ZnO:Al to form Zn_0.88Mg_0.12O:Al as TCO layer effectively decreases surface carrier recombination and improves photovoltaic parameters, especially open‐circuit voltage and fill factor. This is the first experimental proof of the concept for optimizing E _C difference between TCO and absorber to minimize surface carrier recombination. Ultimately, conversion efficiency (η ) of CIGSSe solar cell with alternative Cd_0.75Zn_0.25S/Zn_0.79Mg_0.21O/Zn_0.88Mg_0.12O:Al (TCO) layers is enhanced to 20.6%, owing to control of total E _C alignment, which is higher η up to 12.6% relative as compared with the solar cell with traditional CdS/ZnO/ZnO:Al layers.     

Solution‐processed Cu(In,Ga)(S,Se)2 absorber yielding a 15.2% efficient solar cell

The remarkable potential for inexpensive upscale of solution processing technologies is expected to enable chalcogenide‐based photovoltaic systems to become more widely adopted to meet worldwide energy needs. Here, we report a thin‐film solar cell with solution‐processed Cu(In,Ga)(S,Se)₂ (CIGS) absorber. The power conversion efficiency of 15.2% is the highest published value for a pure solution deposition technique for any photovoltaic absorber material and is on par with the best nonvacuum‐processed CIGS devices. We compare the performance of our cell with a world champion vacuum‐deposited CIGS cell and perform detailed characterization, such as biased quantum efficiency, temperature‐dependent electrical measurement, time‐resolved photoluminescence, and capacitance spectroscopy. Copyright © 2012 John Wiley & Sons, Ltd.     

Construction of ZnS/Sb2S3 Heterojunction as an Ion-Transport Booster toward High-Performance Sodium Storage

Metal sulfides have shown great promise for sodium-ion batteries due to their excellent redox reversibility and relatively high capacity. However, metal sulfides generally suffer from sluggish charge transport and serious volume change during the charge–discharge process. Herein, potato chip-like nitrogen-doped carbon-coated ZnS/Sb₂S₃ heterojunction (ZnS/Sb₂S₃@NC) is precisely synthesized through a sulfurization reaction, and a subsequent metal cation exchange process between Zn²⁺ and Sb³⁺. The theoretical calculations and experimental studies reveal the boosted charge transfer in ZnS/Sb₂S₃@NC composites. Therefore, the ZnS/Sb₂S₃@NC electrode exhibits excellent cycling stability (a high reversible capacity of 511.4 mAh g^-1 after 450 cycles) and superior rate performance (400.4 mAh g^-1 at 10 A g^-1). In addition, ZnS/Sb₂S₃@NC is based on a conversion-alloy reaction mechanism to store Na⁺, which is disclosed by the X-ray diffraction and high resolution transmission electron microscopy analysis. This effective synthesis method can provide a reference for the design of other high-performance electrode materials for sodium-ion batteries.     

Achievement of 17.9% efficiency in 30 × 30 cm2 Cu(In,Ga)(Se,S)2 solar cell sub‐module by sulfurization after selenization with Cd‐free buffer

We have achieved 17.9% efficiency in a 30 × 30 cm² Cu(In,Ga)(Se,S)₂ solar cell sub‐module prepared by selenization and sulfurization processes with a Cd‐free buffer. The development of an absorber layer, transparent conducting oxide window layer, and module design was the key focus. This permitted 1.8% higher efficiency than our last experimental result. The quantity and the injection time of the sodium were controlled, resulting in higher open circuit voltage (V_oc) and short circuit current (J_sc). In order to increase J_sc, we changed the thickness of the window layer. Boron‐doped zinc oxide was optimized for higher transmittance without reducing the fill factor. The uniformity of each layer was improved, and patterns were optimized for each module. Therefore, V_oc, J_sc, and FF could be theoretically improved on the reported results of, respectively, 20 mV, 2 mA/cm², and 1.4%. The module's efficiency was measured at the Korea Test Laboratory to compare with the data obtained in‐house. Various analyses were performed, including secondary ion mass spectroscopy, photoluminescence, quantum efficiency, solar simulator, and UV–vis spectrometry, to measure the cell's depth profile, carrier lifetime, external quantum efficiency, module efficiency, and transmittance, respectively. Copyright © 2015 John Wiley & Sons, Ltd.     

基于三氯氧磷液态源扩散技术的太阳能电池转换效率研究

通过对太阳能电池片扩散工艺中扩散端POCl3流量的控制实验,研究了POCl3流量对所制太阳能电池的等效串联电阻RS、漏电阻RSH以及转换效率的影响。结果表明:RS和RSH都随POCl3流量减小而增大。当POCl3流量为950 mL/min时,所制太阳能电池转换效率达到最大值16.69%,比常规生产(POCl3流量为1 000 mL/min)的转换效率提高了0.35%。