Publications by authors named "Dongxing Kou"

Article Synopsis
  • * While adding silver (Ag) helps reduce these defects, it also causes lower electrical conductivity and carrier density, limiting cell performance.
  • * The proposed solution involves a combined Ag and hydrogen (H) doping method, which enhances conductivity and reduces defects, achieving a notable efficiency of 14.74% in CZTSSe devices.
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It has been validated that enhancing crystallinity and passivating the deep-level defect are critical for improving the device performance of kesterite CuZnSn(S,Se) (CZTSSe) solar cells. Coordination chemistry interactions within the Cu-Zn-Sn-S precursor solution play a crucial role in the management of structural defects and the crystallization kinetics of CZTSSe thin films. Therefore, regulating the coordination environment of anion and cation in the precursor solution to control the formation process of precursor films is a major challenge at present.

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Article Synopsis
  • High-quality CZTSSe solar cells require improved crystal structure and fewer defects for better open-circuit voltage and efficiency.
  • A new segmented control strategy for the selenization process is introduced to better manage the evaporation of selenium, which enhances film quality during growth.
  • This method reduces defects and improves carrier collection, achieving a solar cell efficiency of 13.77% with low voltage deficit.
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Kesterite CuZnSn(S,Se) (CZTSSe) has been considered as the most promising absorber material for inorganic thin-film solar cells. Among the three main interfaces in CZTSSe-based solar cells, the CZTSSe/Mo back interface plays an essential role in hole extraction as well as device performance. During the selenization process, the reaction between CZTSSe and Mo is one of the main reasons that lead to a large open circuit voltage () deficit, low short circuit current (), and fill factor.

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Grain boundaries (GBs)-triggered severe non-radiative recombination is recently recognized as the main culprits for carrier loss in polycrystalline kesterite photovoltaic devices. Accordingly, further optimization of kesterite-based thin film solar cells critically depends on passivating the grain interfaces of polycrystalline Cu ZnSn(S,Se) (CZTSSe) thin films. Herein, 2D material of graphene is first chosen as a passivator to improve the detrimental GBs.

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Solar cells based on emerging kesterite CuZnSn(S,Se) (CZTSSe) materials have reached certified power conversion efficiency (PCE) as high as 13.6%, showing great potential in the next generation of photovoltaic technologies because of their earth-abundant, tunable direct bandgap, high optical absorption coefficient, environment-friendly, and low-cost properties. The predecessor of CZTSSe is Cu(In,Ga) Se (CIGS), and the highest PCE of CIGS fabricated by the vacuum method is 23.

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The main bottleneck in the development of kesterite CuZnSn(S,Se) (CZTSSe) solar cells is their very low due to severe carrier recombination. Specifically, due to the poor defect environment and unfavorable band structure, carrier recombination at the front interface is considered to be one of the most serious issues. Thus, to reduce the interface recombination and deficit, we propose a convenient and effective strategy for Cd gradient doping near the front interface during selenization.

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Solution processing of Cu(In,Ga)Se (CIGS) absorber is a highly promising strategy for a cost-effective CIGS photovoltaic device. However, the device performance of solution-processed CIGS solar cells is still hindered by the severe non-radiative recombination resulting from deep defects and poor crystal quality. Here, a simple and effective precursor film engineering strategy is reported, where Cu-rich (CGI >1) CIGS layer is incorporated into the bottom of the CIGS precursor film.

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The kesterite CuZnSn(S,Se) (CZTSSe) solar cells have shown a continuous rise in power conversion efficiencies in the past years. However, the encountered interfacial problems with respect to charge recombination and extraction losses at the CdS/CZTSSe heterojunction still hinder their further development. In this work, an additional plasmonic local electric field is imposed into the CdS/CZTSSe interface through the electrostatic assembly of a two-dimensional (2D) ordered Au@SiO NP array onto an aminosilane-modified surface absorber.

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Indium doping of cadmium sulfide (CdS) by chemical bath deposition (CBD) can be an efficient strategy to boost the CIGSSe efficiency. However, limited by the extremely low solubility of InS, it is difficult to increase the In doping contents and inhibit the band energy-level regulation for CdS through the traditional CBD process. In this work, we perform a novel CBD method to prepare an indium-doped CdS (In:CdS) buffer, in which the indium source is sequentially slowly added in the growing aqueous solution.

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Although the traditional Cu-poor architecture addresses many limitations for CuZnSn(S,Se) solar cells, its further development still encounters a bottleneck in terms of efficiency, primarily arising from the inferior charge transport within the quasineutral region and enlarged recombination at back contact. On the contrary, the electrical benign kesterite compound with higher Cu content may compensate for these shortages, but it will degrade device performance more pronouncedly at front contact because of the Fermi level pinning and more electric shunts. Based on the electric disparities on their independent side, in this work, we propose a new status of Cu component by exploring a large grain/fine grain/large grain trilayer architecture with higher Cu content near back contact and lower Cu content near front contact.

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Material crystallinity is the overriding factor in the determination of the photoelectric properties of absorber materials and the overall performance of the photovoltaic device. Nevertheless, in the CuZnSn(S,Se) (CZTSSe) photovoltaic device, the bilayer or trilayer structure for the absorber has been broadly observed, which is generally harmful to the cell performance because the probability of photogenerated carrier recombination at grain boundaries significantly increased. Herein, our experiment reveals that the application of anions to a new family of (Cu,Ag)ZnSn(S,Se) (CAZTSSe) materials leads to an increase in grain size and crystallinity.

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Cu(In,Ga)Se (CIGS) is considered a promising photovoltaics material due to its excellent properties and high efficiency. However, the complicated deep defects (such as In or Ga) in the CIGS layer hamper the development of polycrystalline CIGS solar cells. Numerous efforts have been employed to passivate these defects which distributed in the grain boundary and the CIGS/CdS interface.

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The earth-abundant CuZnSnS (CZTS) quantum dots (QDs) have emerged as one potential substitute to toxic cadmium or rare indium QDs, but their application in quantum dot-sensitized solar cells (QDSSCs) is still limited by the improper particle size and the rigorous synthesis and ligand exchange conditions. Herein, we developed a one-pot hot injection method by using Tri-n-octylphosphine oxide (TOPO) as the solvent and oleylamine as the capping agent to synthesize CuZnSn(S,Se) (CZTSSe) QDs with adjustable size and narrow size distribution. The key feature of this approach is that we can take advantage of the high-temperature nucleation, low-temperature growth, and strong reducibility of NaHB to prepare small-sized CZTSSe QDs without using 1-dodecanethiol (DDT) and to extend the light harvesting range through Se incorporation.

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Hybrid nanostructures comprising conjugated polymers (CPs) and plasmonic metals show excellent performance in light harvesting. However, the energy transfer mechanism of the CP film to nearby metal nanoparticles, especially knowledge of the characteristic distance, is still unclear. Here, quenching of the emission of a CP film in proximity to a monolayer of graphene-nanodot-supported silver nanoparticles (GND-Ag NPs) is investigated.

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In this study, ZnO nanotubes (ZNTs) were prepared onto fluorine-doped tin oxide (FTO) glass and used as supports for MIPs arrays fabrication. Due to the imprinted cavities are always located at both inner and outer surface of ZNTs, these ZNTs supported MIPs arrays have good accessibility towards template and can be used as sensing materials for chemical sensors with high sensitivity, excellent selectivity and fast response. Using K[Fe(CN)] as electron probe, the fabricated electrochemical sensor shows two linear dynamic ranges (0.

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The partial substitution of Cu with Ag into the host lattice of CuZnSn(S,Se) thin films can reduce the open-circuit voltage deficit (V) of CuZnSn(S,Se) (CZTSSe) solar cells. In this paper, elemental Cu, Ag, Zn, Sn, S, and Se powders were dissolved in solvent mixture of 1,2-ethanedithiol (edtH) and 1,2-ethylenediamine (en) and used for the formation of (CuAg)ZnSn(S,Se) (CAZTSSe) thin films with different Ag/(Ag + Cu) ratios. The key feature of this approach is that the impurity atoms can be absolutely excluded.

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p-type inorganic hole transport materials of Li, Cu-codoped NiOx films were deposited using a simple solution-based process. The as-prepared films were used as hole selective contacts for lead halide perovskite solar cell. An enhanced power conversion efficiency of 14.

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The properties of thin titanium dioxide blocking layers onto TCO in dye-sensitized solar cells (DSCs) have been widely reported as their intensity dependence of illumination intensity. Herein, a further investigation about their functioning with the effect of temperature is developed. The electron recombination process, photovoltage response on illumination intensity and photocurrent-voltage properties for DSCs with/without blocking layer at different temperatures are detected.

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Solution-processed approach for the deposition of Cu2ZnSn (S,Se)4 (CZTSSe) absorbing layer offers a route for fabricating thin film solar cell that is appealing because of simplified and low-cost manufacturing, large-area coverage, and better compatibility with flexible substrates. In this work, we present a simple solution-based approach for simultaneously dissolving the low-cost elemental Cu, Zn, Sn, S, and Se powder, forming a homogeneous CZTSSe precursor solution in a short time. Dense and compact kesterite CZTSSe thin film with high crystallinity and uniform composition was obtained by selenizing the low-temperature annealed spin-coated precursor film.

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Cu2ZnSnSxSe4-x (CZTSSe) counter electrodes (CEs) in dye-sensitized solar cells (DSSCs) are commonly developed with porous structures, but their high surface area could also retard electron transport processes owing to the abundant grain boundaries. Herein, we employed a convenient solution method and a rapid heating process to prepare well crystalline CZTSSe CEs in DSSCs. The influence of crystallization of CZTSSe film on DSSCs performances was discussed in depth.

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CZTS exhibited apparently phase-dependent photocatalytic H2 evolution under visible light. Possible factors for the phase-dependent photocatalytic activity of CZTS were discussed in detail.

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In this work, we employed a convenient one-step synthesis method for synthesizing Cu2ZnSnSe4 (CZTSe) nanocrystals (NCs) in an excess selenium environment. This excess selenium situation enhanced the reaction of metal acetylacetonates with selenium, resulting in the burst nucleation of NCs at relatively low temperatures. The phase morphology and surface and optoelectronic properties of NCs before and after ligand exchange were discussed in depth.

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A simple solution-processing method was employed to fabricate panchromatic mp-TiO2/CH3NH3PbI3/P3HT-MWNT/Au solar cells. MWNTs in a P3HT-MWNT composite acted as efficient nanostructured charge transport tunnels and induce crystallization of P3HT, hence significantly enhancing the conductivity of the composite. The fill factor of the hybrid solar cells was greatly enhanced by 26.

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