PSS Solar Cells Research Articles

InP QDs modified GaAs/PEDOT:PSS hybrid solar cell with efficiency over 15.

GaAs heterojunction solar cells are known as promising substitutions for traditional GaAs solar cells for their low cost and performance potential. Nevertheless, the further performance enhancement is hindered by insufficient spectral absorption and nonradioactive recombination. In this work, an InP quantum dot (QD) modified GaAs/PEDOT:PSS solar cell is designed to enhance spectrum utilization and suppress the nonradioactive carriers loss and the solar cell efficiency at 15.08% is achieved. Furthermore, InP QDs used in this work are synthesized by a novel hydrothermal method. During the synthesis process, β-cyclodextrin (β-cyc) was introduced into the reactants and acted as a reaction cell, isolating water and oxygen, enabling the reaction to proceed in ambient air. InP QDs synthesized by this method can achieve band engineering by altering reactant ratios, thereby effectively serving as both a Luminescent Solar Concentrator (LSC) and a Front Surface Field (FSF) in GaAs/PEDOT:PSS solar cells. This work demonstrates an inspiring way to synthesize InP QDs and optimize the performance of GaAs hybrid solar cells.

Improving the Performance of Si/PEDOT:PSS Hybrid Solar Cells with More Economical and Environmentally Friendly Alcohol Ether Solvents.

The photoelectric characteristics of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) films significantly affect the power conversion efficiency and stability of Si/PEDOT:PSS hybrid solar cells. In this paper, we investigated PEDOT:PSS modification with alcohol ether solvents (dipropylene glycol methyl ether (DPM) and propylene glycol phenyl ether (PPH)). The reduction of PSS content and the transformation of the PEDOT chain from benzene to a quinone structure in PEDOT:PSS induced by doping with DPM or PPH are the reasons for the improved conductivity of PEDOT:PSS films. DPM and PPH doping improves the quality of silicon with the PEDOT:PSS heterojunction and silicon surface passivation, thereby reducing the surface recombination of charge carriers, which improves the photovoltaic performance of Si/PEDOT:PSS solar cells. Comparing the power conversion performance (PCE) and air stability of Si/PEDOT:PSS solar cells with DPM (13.24%), DPH (13.51%), ethylene glycol (EG, 13.07%), and dimethyl sulfoxide (DMSO, 12.62%), it is suggested that doping with DPM and DPH can replace DMSO and EG to enhance the performance of Si/PEDOT:PSS solar cells. The EG and DMSO solvents not only have a certain toxicity to the human body but also are not environmentally friendly. In comparison to DMSO and EG, DPM and DPH are more economical and environmentally friendly, helping to reduce the manufacturing cost of Si/PEDOT:PSS solar cells and making them more conducive to their commercial applications.

Unlocking the plasma advantage in elevating the performance of silicon nanowires/ poly(3,4-ethylenedioxythiophene): Poly(styrenesulfonate) hybrid solar cell

Silicon Nanowires (SiNWs) can be easily synthesized by following the two-step electroless metal-assisted chemical etching method. These SiNWs are well known for their low reflectivity due to their excellent light-harvesting characteristics. In this paper, we demonstrated the effect of plasma treatment time on the performance of SiNWs solar cells. The 1 min plasma-treated SiNWs/Poly 3,4-[ethylene dioxy thiophene:Polystyrene sulfonate] (PEDOT׃PSS) solar cell showed increased power conversion efficiency than the untreated SiNWs/PEDOT׃PSS solar cell. The photo Current density-Voltage (J-V) analysis showed that the open circuit voltage (VOC) of the plasma treated solar cell for 1 min is higher (270 mV) than that of the untreated solar cell (120 mV). The increase in the value of VOC comes from different factors׃ one is due to the formation of a good interface between the SiNWs and PEDOT׃PSS layer; other is the reduction of defect densities in SiNWs/PEDOT׃PSS heterojunction, consequently the reduction in the recombination processes. Hence from this research, we found that by controlling the plasma treatment on SiNWs, it can improve the SiNWs properties which can further improve the efficiency of the solar cell.

Phosphorus and Selenium Co‐Doped WO3 Nanoparticles for Interface Modification and Photovoltaic Properties Enhancement of Monolayer Planar Silicon/PEDOT:PSS Hybrid Solar Cells

AbstractOrganic/silicon hybrid solar cells have attracted extensive attention owing to their low cost and simple manufacturing process. However, theoretical simulations indicate that the efficiency of organic/silicon hybrid solar cells should exceed 20%. This study demonstrates phosphorus and selenium co‐doped WO3 nanoparticles used for heterojunction solar cell (HSC) modification and theoretically elaborates the effects of these doping elements. The doped WO3 nanoparticles are added into poly(3,4‐ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) films to optimize the physical properties and qualities of the organic layer. The admixture of P/Se‐WOx greatly improves the open‐circuit voltage and fill factor of Si/PEDOT:PSS solar cell devices. In the hole transport layer (HTL)‐based device, the P/Se‐WOx hybrid PEDOT:PSS HTL yields a power conversion efficiency up to 13.64%, which is substantially higher than those of previously reported undoped and doped devices. The generated W5+ in optimized WO3 further indicates that the VI B group elements, such as W or Mo with 5+ state ions, positively influence the HSC performance and would greatly benefit the photovoltaic industry.

Methyl passivation is better than silicon oxide passivation in five aspects for the Si/PEDOT:PSS interface

Methyl passivation has been demonstrated to be better than the silicon oxide passivation commonly used in Si/PEDOT:PSS solar cells; however, the reason is still unclear. Based on first-principle calculations on the carrier transport behaviors at the Si/PEDOT:PSS interface, we found that methyl passivation is superior to silicon oxide passivation in five aspects. First, methyl plays better than silicon oxide in eliminating the dangling bonds and introducing fewer defect levels in the bandgap. Secondly, the effective carrier mass in methyl passivated Si substrate is smaller than silicon oxide passivated. Thirdly, the carrier transfer rate through the Si/PEDOT:PSS interface with methyl passivation will be much larger than that with silicon oxide passivation. Fourthly, an additional electric field that can boost the separation of carriers will form at the methyl passivated Si/PEDOT:PSS interface. Finally, the energy band bending of the Si substrate with methyl passivation, ∼0.08 eV, will not hinder the holes extraction as significantly as that with silicon oxide passivation, ∼0.63 eV. This article provides a complete process for evaluating a passivation scheme based on first-principle calculations.

Antireflection Improvement and Junction Quality Optimization of Si/PEDOT:PSS Solar Cell with the Introduction of Dopamine@Graphene

Si/PEDOT: PSS solar cell is an optional photovoltaic device owing to its promising high photovoltaic conversion efficiency (PCE) and economic manufacture process. In this work, dopamine@graphene was firstly introduced between the silicon substrate and PEDOT:PSS film for Si/PEDOT: PSS solar cell. The dopamine@graphene was proved to be effective in improving the PCE, and the influence of mechanical properties of dopamine@graphene on solar cell performance was revealed. When dopamine@graphene was incorporated into the cell preparation, the antireflection ability of the cell was enhanced within the wavelength range of 300~450 and 650~1100 nm. The enhanced antireflection ability would benefit amount of the photon-generated carriers. The electrochemical impedance spectra test revealed that the introduction of dopamine@graphene could facilitate the separation of carriers and improve the junction quality. Thus, the short-circuit current density and fill factor were both promoted, which led to the improved PCE. Meanwhile, the influence of graphene concentration on device performances was also investigated. The photovoltaic conversion efficiency would be promoted from 11.06% to 13.15% when dopamine@graphene solution with concentration 1.5 mg/mL was applied. The achievements of this study showed that the dopamine@graphene composites could be an useful materials for high-performance Si/PEDOT:PSS solar cells.

Silicon Substrate Treated with Diluted NaOH Aqueous for Si/PEDOT: PSS Heterojunction Solar Cell with Performance Enhancement

Si/PEDOT: PSS solar cell is an important alternative for photovoltaic device due to its anticipated high theoretical efficiency and simple manufacturing process. In this study, processing silicon substrate with diluted NaOH aqueous solution was found to be an effective method for improving device performance, one that notably improves junction quality and light trapping ability. When immersed in diluted NaOH aqueous solution, the junction quality was improved according to the enlarged fill factor, reduced series resistance, and enhanced minor carrier lifetime. The diluted NaOH aqueous solution immersion etched the silicon surface and helped with the enhancement of light trapping ability, further improving the short-circuit current density. Although diluted NaOH aqueous solution immersion for bare silicon could improve the performance of devices, proper immersion time was needed. The influence of immersion time on device performances was investigated. The photovoltaic conversion efficiency easily increased from 10.01% to 12.05% when silicon substrate was immersed in diluted NaOH aqueous for 15 min. This study contributes to providing efficient and convenient methods for preparing high performance Si/PEDOT: PSS solar cells.

Planar Organic‐Si Hybrid Solar Cell with MoOx Mixed PEDOT:PSS as Hole Injection Layer Profits from Mo5+ and Mo6+ Synergistic Effects

AbstractPoly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hole injection layer plays an important role in planar Si/PEDOT:PSS heterojunction solar cells (HSCs). Herein, a MoOx mixed aqueous PEDOT:PSS cosolvent is developed and is applied into a Si/PEDOT:PSS solar cell preparation via a time‐saving one‐step spin‐coating method. With an optimal concentration of MoOx dopants, the power conversion efficiency of the device exhibits from 10.26% up to 13.82% with all inherent photovoltaic parameters enhanced. The detailed characterization and analytical results indicate that an advanced electronic property is produced by MoOx dopants and interface optimization caused by synergistic effects from Mo5+ and Mo6+ species with PEDOT:PSS, which enhances its interface work function and promotes hole transportation capacity. The result paves a path for exploring efficient Si/PEDOT:PSS HSCs with suitable functional material and a simple solution‐processable method.

The ideal doping concentration of silicon wafer for single junction hybrid n-Si /PEDOT: PSS solar cells with 3.2% elevated PCE and Voc of 620 mV

Increasing the open circuit voltage of organic/Si-based hetero-junction solar cells (HSCs) is an efficient path for improving its photoelectric conversion efficiency (PCE). Commonly, increasing the doping concentration (ND) for silicon planar substrate could enhance the open circuit voltage (Voc). Comparing with other groups used 1015 cm−3 and other various doping level, the selected 1017 cm−3 doping concentration, as the ideal doping level, could enhance 100 mV for Voc and maximum increase the PCE up to 12.54% without any additional antireflection (AR) layer deposition. To our knowledge, this obtained Voc of 620 mV is a prominent reported value for n-Si/PEDOT: PSS solar devices without any additional antireflection (AR) layer deposition. Meanwhile, this research work clarifies that the PCE is inconsistently increased with the doping concentration, and 1018 cm−3 or higher doping concentration would import internal defects and reduce the PEC. This investigation of silicon wafer’s optimal doping level paves a utility way for easily enhancing the efficiency of industrialized Si/PEDOT: PSS solar cells with low-cost fabrication technologies.

Performance of Si/PEDOT:PSS Solar Cell Controlled by Dipole Moment of Additives

Solar cells composed of silicon (Si) and polymer films have attracted much attention because of their high performance and facile preparation using aqueous solutions. Although a large amount of research has been carried out to further improve their performance, the factors required to achieve this are not yet fully understood from the perspective of physical chemistry. Here, we show the effect of additives on the performance of Si/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) solar cells using six different additives. The relationships among the solar cell performance, electrical properties, and the structure of the polymer film are examined by changing the additive and conducting cyclic voltammetry, electric conductivity, and two-dimensional grazing incidence angle X-ray diffraction measurements. The dipole moment of the additive molecule was determined to be a key factor for improving the performance of Si/PEDOT:PSS solar cells. In particular, an additive with a higher dipole momen...

Effect of Gold Nanospheres and Nanodots on the Performance of PEDOT:PSS Solar Cells.

Gold nanospheres were synthesized using a modified Turkevich method (d = 14±4 nm, λmax = 531 nm), while gold nanodots made of spheres (5±2 nm) and non-spherical nanodots (aspect ratio of 1.7±0.4) were synthesized using a modified seed mediated method. The spherical gold nanodots exhibited a transverse excitation mode at 525 nm while the non-spherical gold nanodots showed an additional longitudinal excitation mode observed in the UV-vis spectrum at 794 nm. The gold nanodots also exhibited a surface enhanced Raman effect which significantly influenced the electronic properties of the photovoltaic device. The incorporation of Au nanospheres in a PEDOT:PSS hole transport layer increased the photovoltaic device efficiency by 51%. This was attributed to a decrease in the series resistance which improved the hole transport pathways in the PEDOT:PSS and enhanced the current density of the photovoltaic device. In contrast, incorporation of spherical and non-spherical gold nanodots into the PEDOT:PSS hole transport layer resulted in a decrease in current density and a consequent decrease in efficiency. This can be attributed to the electron-hole recombination and accumulation of space charges by the non-spherical gold nanodots in PEDOT:PSS resulting in an increased series resistance and leakage currents and hence a reduced device performance. Thus, the morphological, structural and opto-electrical properties of the gold nanospheres and nanodots influenced the device performance of the PEDOT:PSS solar cells.

Efficient Planar Hybrid n-Si/PEDOT:PSS Solar Cells with Power Conversion Efficiency up to 13.31% Achieved by Controlling the SiOx Interlayer

In this work, the effects of the SiOx interface layer grown by exposure in air on the performance of planar hybrid n-Si/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) solar cells are investigated. Compared to the cell with a hydrogen-terminated Si surface, the cell with an oxygen-terminated Si surface reveals improved characteristics in power conversion efficiency, increased from 10.44% to 13.31%. By introducing the SiOx, the wettability of the Si surface can be improved, allowing an effective spread of the PEDOT:PSS solution and thus a good contact between the PEDOT:PSS film and Si. More importantly, it can change the polarity of the Si surface from a negative dipole to a positive dipole, owing to the introduction of the SiOx interface. The Si energy band will bend up and give rise to a favorable band alignment between Si and PEDOT:PSS to promote carrier separation. These results could be potentially employed to further development of this simple, low-cost heterojunction solar cell.

Naphthalene Diimide-Based n-Type Polymers: Efficient Rear Interlayers for High-Performance Silicon-Organic Heterojunction Solar Cells.

Silicon-organic heterojunction solar cells suffer from a noticeable weakness of inefficient rear contact. To improve this rear contact quality, here, two solution-processed organic n-type donor-acceptor naphthalene diimide (NDI)-based conjugated polymers of N2200 and fluorinated analogue F-N2200 are explored to reduce the contact resistance as well as to passivate the Si surface. Both N2200 and F-N2200 exhibit high electron mobility due to their planar structure and strong intermolecular stacking, thus allowing them to act as excellent transporting layers. Preferential orientation of the polymers leads to reduce contact resistance between Si and cathode aluminum, which can enhance electron extraction. More importantly, the substitution of fluorine atoms for hydrogen atoms within the conjugated polymer can strengthen the intermolecular stacking and improve the polymer-Si electronic contact due to the existence of F···H interactions. The power conversion efficiencies of Si-PEDOT:PSS solar cells increased from 12.6 to 14.5% as a consequence of incorporating the F-N2200 polymer interlayers. Subsequently, in-depth density functional theory simulations confirm that the polymer orientation plays a critical role on the polymer-Si contact quality. The success of NDI-based polymers indicates that planar conjugated polymer with a preferred orientation could be useful in developing high-performance solution-processed Si-organic heterojunction photovoltaic devices.

Nanostructural optimization of silicon/PEDOT:PSS hybrid solar cells for performance improvement

In this paper, an inverted silicon (Si) nanopyramid (iSiNP) surface structure with low aspect ratio and remarkable antireflection is developed through sequential treatments of NaOH and HF/CH3COOH/HNO3 solutions to Si nanowire (SiNW)-textured Si wafers, which are prepared by traditional electroless chemical etching. The iSiNP/PEDOT:PSS hybrid solar cell is fabricated through conformally spin-coating poly(3.4-ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) onto the iSiNPs; it exhibits enhanced device performance owing to the improved junction and contact quality as compared to the SiNW/PEDOT:PSS counterpart. A power conversion efficiency (PCE) of 9.6% mainly contributed from an increased fill factor (FF) of 0.61 and improved open circuit voltage (Voc) of 0.53 V is delivered by the iSiNP/PEDOT:PSS solar cell. As a comparison, the SiNW/PEDOT:PSS structure delivers a 7.1% PCE with a FF of 0.45 and Voc of 0.46 V. Considering the submicro-scale characteristic dimensions, iSiNPs are expected to be applicable to highly efficient thin film Si/PEDOT:PSS hybrid solar cells.

Hole-Transporting Layer Treatment of Planar Hybrid n-Si/PEDOT:PSS Solar Cells with Power Conversion Efficiency up to 14.5%

A systematical investigation was carried out into the effects of the hole-transporting layer treatment of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) on the performance of planar hybrid n-Si/PEDOT:PSS solar cells. Triton X-100 and ethylene glycol (EG) were chosen to improve the conductivity and surface morphology of the PEDOT:PSS film. It was found that the annealing temperature has a great influence on the PEDOT:PSS material properties and the corresponding device performance. By optimizing the annealing temperature, the conductivity of the PEDOT:PSS film doped with Triton X-100 and EG could be enhanced by a factor of more than three orders. And the corresponding device also shows record power conversion efficiency as high as 14.5% with an open circuit voltage of 0.627 V, a short circuit current of 32.6 mA/cm2, and a fill factor of 70.7%.

Efficiency improvement in silicon nanowire/conductive polymer hybrid solar cells based on formic acid treatment

The mechanisms causing the improvement of PCE in hybrid SiNWs/PEDOT:PSS solar cells by formic acid treatment were investigated.

Si/PEDOT:PSS hybrid solar cells incorporated with silver plasmonic nanospheres

We study the incorporation of periodic silver nanospheres on planar hybrid Si/PEDOT:PSS solar cell for absorption enhancement based on the plasmonic effect. The impact of the periodicity and diameter of the silver nanospheres on the light absorption of the hybrid cell is systematically simulated using the finite element method. The light absorption is found to improve significantly in the presence of the silver nanospheres, achieving a maximum ultimate efficiency of 22.6% when the periodicity is 600nm and the nanosphere diameter to periodicity ratio is 0.45. This is 23.8% higher than that of the planar hybrid thin cell without the silver nanospheres. The physics behind the enhanced light absorption in the hybrid cell arising from the introduction of periodic silver nanospheres is also discussed.

High Efficiency Organic/Silicon-Nanowire Hybrid Solar Cells: Significance of Strong Inversion Layer.

Organic/silicon nanowires (SiNWs) hybrid solar cells have recently been recognized as one of potentially low-cost candidates for photovoltaic application. Here, we have controllably prepared a series of uniform silicon nanowires (SiNWs) with various diameters on silicon substrate by metal-assisted chemical etching followed by thermal oxidization, and then fabricated the organic/SiNWs hybrid solar cells with poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS). It is found that the reflective index of SiNWs layer for sunlight depends on the filling ratio of SiNWs. Compared to the SiNWs with the lowest reflectivity (LR-SiNWs), the solar cell based on the SiNWs with low filling ratio (LF-SiNWs) has a higher open-circuit voltage and fill factor. The capacitance-voltage measurements have clarified that the built-in potential barrier at the LF-SiNWs/PEDOT:PSS interface is much larger than that at the LR-SiNWs/PEDOT one, which yields a strong inversion layer generating near the silicon surface. The formation of inversion layer can effectively suppress the carrier recombination, reducing the leakage current of solar cell, and meanwhile transfer the LF-SiNWs/PEDOT:PSS device into a p-n junction. As a result, a highest efficiency of 13.11% is achieved for the LF-SiNWs/PEDOT:PSS solar cell. These results pave a way to the fabrication of high efficiency organic/SiNWs hybrid solar cells.

Substantial Improvement of Short Wavelength Response in n-SiNW/PEDOT:PSS Solar Cell.

We report herein on the effects of silicon nanowire with different morphology on the device performance of n-SiNW/PEDOT:PSS hybrid solar cells. The power conversion efficiency (PCE) and external quantum efficiency (EQE) of the SiNW/PEDOT:PSS hybrid solar cells can be optimized by varying the length of the silicon nanowires. The optimal length of silicon nanowires is 0.23 μm, and the hybrid solar cell with the optimal length has the Voc of 569 mV, Jsc of 30.1 mA/cm2, and PCE of 9.3 %. We fabricated more isolated silicon nanowires with the diluted etching solution. And the Jsc of the hybrid solar cell with more isolated nanowires has a significant enhancement, from 30.1 to 33.2 mA/cm2. The remarkable EQE in the wavelength region of 300 and 600 nm was also obtained, which are in excess of 80 %. Our work provides a simple method to substantially improve the EQE of hybrid solar cell in the short wavelength region.

Junction formation and current transport mechanisms in hybrid n-Si/PEDOT:PSS solar cells.

We investigated hybrid inorganic-organic solar cells combining monocrystalline n-type silicon (n-Si) and a highly conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS). The build-in potential, photo- and dark saturation current at this hybrid interface are monitored for varying n-Si doping concentrations. We corroborate that a high build-in potential forms at the hybrid junction leading to strong inversion of the n-Si surface. By extracting work function and valence band edge of the polymer from ultraviolet photoelectron spectroscopy, a band diagram of the hybrid n-Si/PEDOT:PSS heterojunction is presented. The current-voltage characteristics were analyzed using Schottky and abrupt pn-junction models. The magnitude as well as the dependence of dark saturation current on n-Si doping concentration proves that the transport is governed by diffusion of minority charge carriers in the n-Si and not by thermionic emission of majorities over a Schottky barrier. This leads to a comprehensive explanation of the high observed open-circuit voltages of up to 634 mV connected to high conversion efficiency of almost 14%, even for simple planar device structures without antireflection coating or optimized contacts. The presented work clearly shows that PEDOT:PSS forms a hybrid heterojunction with n-Si behaving similar to a conventional pn-junction and not, like commonly assumed, a Schottky junction.