Heterojunction Hybrid Solar Cells Research Articles

Interfacial Band Engineering of Highly Efficient PEDOT:PSS/p‐Si/ZnO Heterojunction Solar Cells

Hybrid heterojunction solar cells (HHSCs) using different active materials as hole‐selective transport layers and electron‐selective transport layers show great potential in both low cost and high power conversion efficiency (PCE). Herein, PEDOT:PSS/p‐Si/ZnO backcontact heterojunction solar cells are prepared using the simple low‐temperature solution method. PEDOT:PSS is introduced into p‐Si‐based solar cells as an antireflective and passivation layer to optimize device performance. The effect of the work function (WF) of ZnO on device performance is investigated, and a PCE of 10.74% is achieved using low‐WF ZnO. In addition, the PEDOT:PSS layer is doped with Nafion, and the surface passivation quality of the p‐Si is dramatically enhanced. By optimizing the doping concentration of Nafion, the PCE of the optimized device reaches 11.43%, which is currently the highest PCE for p‐Si‐based solar cells using solution method. The findings provide a simple and promising method to achieve high‐performance PEDOT:PSS/p‐Si/ZnO HHSCs.

Rapid and low temperature micro inverted pyramid texturing of silicon via copper catalyzed chemical etching for high efficiency PEDOT:PSS/silicon hybrid solar cells

Here, a rapid, low-temperature yet effective micro-inverted structuring of silicon (Si) via a low thermal budget copper catalyzed chemical etching (CuCCE) has been demonstrated for efficient hybrid heterojunction solar cells (HSCs) based on poly (3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS)/Si in the basic device design ‘Ag/PEDOT:PSS/n-Si/In:Ga’. The inverted pyramidal (IP) arrays have been obtained on a large area of the partially polished (PP) Si surface by the CuCCE in etch bath consisting of Cu(NO3)2/HF/ H2O2 in 100 mM:4.5 M:1.5 M at room temperature (30 °C). The IP-Si shows significantly reduced total surface reflectance (<7 %) than the PP-Si (>30 %) for broad spectral range. The high efficiency device on the interconnected IP-Si surface shows power conversion efficiency (PCE) >10.75 % which is direct enhancement of ∼4 folds (absolute) when compared with the HSCs made on the PP-Si surface. Such high efficiency HSCs employing the CuCCE based inverted structured solar grade Si surface and detailed analyses of PEDOT:PSS/Si interface have rarely been addressed. The junction property has been studied with the help of Nyquist plots and Mott-Schottky (C-V) analyses of impedance sepctroscopy. A direct 2.9 fold enhancement in the recombination resistance along with high barrier potential found for the optimized IP-Si structured HSCs facilitated the improved junction and minimum recombination at the PEDOT:PSS/n-Si interface. The enhanced PCE is primarily attributed to improved light harvesting ability of the IP-Si surface, junction and passivation properties with conformal coverage of the PEDOT:PSS layer. The study will help to explore the high potential of the CuCCE based IP-Si surfaces for future high efficiency devices.

Carbon nanotubes as hole-selective contacts for high-efficiency full-area GaAs hybrid heterojunction solar cells

A schematic of the full-area GaAs/NP hybrid HJSC configuration and the energy band diagram of its heterojunction upon illumination.

Effects of different interface on the stability of hybrid heterojunction solar cells

With the rapid increase in efficiency of organic-inorganic hybrid solar cells of Si-poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), their poor stability has become an important factor limiting its further development. Here, we demonstrate that the moisture in the air is the main cause for the performance degradation of the hybrid heterojunction solar cells (HHSCs) and innovatively discovered the effect of the Ag electrodes on the degradation of HHSCs. When exposed to air, the growth of the thin oxide layer on the interface of n-Si/PEDOT:PSS and the formation of silver sulfide (Ag2S) on the Ag/PEDOT:PSS interface together caused the increase in the series resistance (Rs) of the HHSCs. The increase in Rs decreases the fill factor (FF) of the HHSCs and thus leads to the degradation of the cell performance.

Effect of anti-reflecting layers on device performance of SWCNTs/Si hetero-junction hybrid solar cells

Single wall carbon nano-tubes/Silicon (SWCNTs-Si) solar cells have the ability of being an ideal substitute to the expensive crystalline based Silicon solar cells because of promising cell efficiency and cost effectiveness. Single wall carbon nanotubes (SWCNTs) thin films are deposited on n-type silicon substrate to obtain heterojunction solar cells. To enhance the performance of these heterojunction solar cells Molybdenum Oxide and Tin Chloride are deposited on SWCNTs/Si substrates respectively. It has been confirmed from Raman spectroscopy that the doping of MoOx has enhanced p type behaviour of SWCNTs, MoOx layer acts as an anti-reflection layer and protects the n-Si and SWCNTs interface from deposition of oxides. While on the other hand SnCl2 acts as antireflection layer, enhances p-type doping of SWCNTs and suppression of recombination. Three hybrid heterojunction solar cells were fabricated by using MoOx on SWCNTs/Si, SnCl2 on SWCNTs/Si and both MoOx and SnCl2 on SWCNTs/Si, respectively. For structural analysis we have performed X-Ray diffraction (XRD) and Raman analysis. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) are performed for surface analysis which confirms the smooth protected layers of MoOx and SnCl2; furthermore confirmed the presence of deposited metal oxide MoOx and SnCl2. Optical properties such as reflectance of thin films studies by UV visible spectroscopy. Maximum efficiency of 8.2% has been obtained by using both MoOx and SnCl2 on SWCNTs/Si solar cell.

Arrays of nano and micro inverted silicon structures via copper catalyzed chemical etching for effective light trapping

Nano/micro structuring of silicon (Si) via chemical approaches have currently acquired a lot of research interests owing to their excellent light trapping abilities in broad spectral range. Here, a comprehensive study on the fabrication of nano/micro-inverted structures via one-step copper (Cu) catalyzed chemical etching (CuCCE) of solar grade n-Si wafers employing the aqueous solution of Cu(NO3)2/HF/H2O2 in various compositions and their light trapping ability are reported. Influence of etch parameters, namely, Cu2+ ions concentration, HF/H2O2 compositions and surface properties of the wafers are systematically investigated on the evolution of different inverted nano- and micro-structured Si surfaces. Arrays of micron-sized inverted pyramids (μ-IP) and nano-micro-hybrid inverted pyramids (n-μ-HIP) have been fabricated on partial polished and as-cut solar grade Si wafers respectively in an optimized compositions of the solution (Cu(NO3)2, HF and H2O2 at 5 mM, 4.6 M and 0.55 M respectively) at 50 °C after 15 min. The surfaces exhibit solar weighted reflection as low as <7% and <5% respectively for a broad spectral range (400–1000 nm; AM1.5G). The n-μ-HIP-Si arrays also exhibited ∼8 fold enhanced Raman signal. Isotropic thinning of Si wafers, nano-porous, and craters like Si structures could also be obtained under appropriate etch conditions. Mechanism of the formation of such inverted structures under different etch conditions have been explained based on the Cu catalyzed, self-controlled electrochemical redox reactions and balancing act of anisotropic-isotropic etching of Si in the CuCCE etch bath. The excellent light trapping properties of the nano/micro structures is also explained. Moreover, the ‘proof of concept’ of application of the inverted nano/micro light trapping structures in the PEDOT:PSS/n-Si hybrid heterojunction solar cells with enhanced performance has also been shown. The Si surfaces via simple yet effective CuCCE process may find applications in other photosensitive devices as well as surface enhanced Raman spectroscopy.

Study on the Fabrication of PEDOT:PSS/Si Hybrid Solar Cells Incorporated with F4TCNQ and VTMO

Poly(3,4-ethylenedioxythiophene) (PEDOT):polystyrenesulfonate (PSS)/Si hybrid heterojunction solar cells (HHSCs) are fabricated by a solution-based synthesis method which combines the advantages of PEDOT:PSS and the superior performance of crystalline silicon. The optimized PEDOT:PSS–2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) hole transport layer (HTL) was used to prepare organosilicon solar cells with a short-circuit current density (Jsc) of 33.33 mA/cm2 and a photoelectric conversion efficiency (η) of 13.23%. The HTL films were found to have increased conductivity by the addition of an electron-accepting dopant (F4TCNQ), obtaining well-defined crystallinity and few defects. In addition, an one-step combination of F4TCNQ with a silane coupling agent (vinyltrimethoxysilane, VTMO) was used to improve the textured device, with a notable efficiency of 14.46% and a Jsc of 33.88 mA/cm2. Our study provides an alternative and easy way to establish organic–inorganic hybrid applications with excellent optoelectronic properties and to gain a deeper understanding of organic semiconductors.

Achieving low contact resistivity in PEDOT:PSS/n-Si solar cells

Good conductivity and transparency in the visible spectrum along with low processing temperatures and ease of fabrication make Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) a widely accepted polymer for organic-inorganic hybrid heterojunction solar cells. Although the overall conductivity of the PEDOT:PSS is high, the PSS segregates more at the surfaces of the deposited film. This leads to high contact resistivity of PEDOT:PSS film with metal and silicon. In this report, we explore the effect of the spin coating rates on the contact resistivity of PEDOT:PSS with the metal and silicon and the associated performance of PEDOT:PSS/n-Si solar cells. Two different spin speeds of 1000 rpm and 4000 rpm were used to deposit the PEDOT:PSS films over silicon. The PEDOT:PSS films were also deposited in single- and double-layer forms. We could achieve very low contact resistivity of PEDOT:PSS with silicon through spin speed optimizations. Hence, the overall performance of the PEDOT:PSS/n-Si solar cells improves with the spin speed for both single- and double-layer PEDOT:PSS film depositions.

High efficiency flexible PEDOT:PSS/silicon hybrid heterojunction solar cells by employing simple chemical approaches

Efficient flexible hybrid solar cells with basic device architecture are demonstrated using the low-cost Si wafers via simple chemical approaches, and may lead to the next-generation flexible optoelectronic applications with 4-fold reduced Si usage.

Dithizone, carminic acid and pyrocatechol violet dyes sensitized metal (Ho, Ba& Cd) doped TiO2/CdS nanocomposite as a photoanode in hybrid heterojunction solar cell

Considering the great importance of nanocomposite based photo-active nanomaterials for a variety of electronics, photonics and photovoltaics application, it is always worth considering to synthesize new hetreostructure. This paper describes the sol-gel and hydrothermal synthesis of metal (holmium, barium, and cadmium) doped TiO2/CdS nanocomposites for photoanode applications. Various characterization techniques, including XRD, FTIR, UV–VIS, EDX, and SEM were used to examine the synthesized heterostructures. The band gap of pure TiO2 NPs is 3.10 eV, which was effectively decreased to 2.16 eV by doping and coupling with CdS. The nanomaterial's crystallinity, crystallite size, morphology and elemental composition were determined by XRD, SEM and EDX, respectively. As sensitizers, the organic dyes dithizone, carminic acid, and pyrocatechol violet were used. FTIR was used to analyze the effective dye grafting on the surface of nanomaterials. In the presence of hole conducting P3HT polymer as solid state electrolyte, the sensitized materials were evaluated for solid state dye-sensitized solar cells. Compared to the reference device, Cd–TiO2/CdS photosensitized using Pyrocatechol violet dye demonstrated the highest efficiency of 2.68% (0.82%). Other parameters of this device, including open circuit voltage (Voc) and short circuit current (Jsc), were determined to be 16.97 mA cm2 and 0.41V, respectively.

Synthesis of Cu-doped ZnO for bulk heterojunction hybrid solar cells

Synthesis of Cu-doped ZnO for bulk heterojunction hybrid solar cells

π-Conjugated Polymers and Their Application in Organic and Hybrid Organic-Silicon Solar Cells.

The evolution and emergence of organic solar cells and hybrid organic-silicon heterojunction solar cells have been deemed as promising sustainable future technologies, owing to the use of π-conjugated polymers. In this regard, the scope of this review article presents a comprehensive summary of the applications of π-conjugated polymers as hole transporting layers (HTLs) or emitters in both organic solar cells and organic-silicon hybrid heterojunction solar cells. The different techniques used to synthesize these polymers are discussed in detail, including their electronic band structure and doping mechanisms. The general architecture and principle of operating heterojunction solar cells is addressed. In both discussed solar cell types, incorporation of π-conjugated polymers as HTLs have seen a dramatic increase in efficiencies attained by these devices, owing to the high transmittance in the visible to near-infrared region, reduced carrier recombination, high conductivity, and high hole mobilities possessed by the p-type polymeric materials. However, these cells suffer from long-term stability due to photo-oxidation and parasitic absorptions at the anode interface that results in total degradation of the polymeric p-type materials. Although great progress has been seen in the incorporation of conjugated polymers in the various solar cell types, there is still a long way to go for cells incorporating polymeric materials to realize commercialization and large-scale industrial production due to the shortcomings in the stability of the polymers. This review therefore discusses the progress in using polymeric materials as HTLs in organic solar cells and hybrid organic-silicon heterojunction solar cells with the intention to provide insight on the quest of producing highly efficient but less expensive solar cells.

High-Efficiency Si/PEDOT:PSS Hybrid Heterojunction Solar Cells Using Solution-Processed Graphene Oxide as an Antireflection and Inversion-Induced Layer

Due to their high photoelectric conversion efficiency (PCE) and low-cost fabrication process, n-type silicon (n-Si)/poly(3, 4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hybrid heter...

Effect of PEDOT:PSS composition on photovoltaic performance of PEDOT:PSS/n-Si hybrid solar cells

Poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonic acid) (PEDOT:PSS) with different composition ratios (α = [PSS]/[PEDOT]) was newly synthesized by chemical oxidative polymerization and organic/inorganic heterojunction hybrid solar cells were fabricated by spin-coating of the PEDOT:PSS water dispersion on n-type silicon wafer. It was found that the photovoltaic performance of the hybrid solar cells was strongly affected by electrical and optical properties of the PEDOT:PSS, where at α = 2.8 the short-circuit current (J sc), open-circuit voltage (V oc), and power conversion efficiency attained 32.1 mA cm−2, 0.521 V, and 11.1%, respectively.

Hybrid heterojunction solar cells based on single‐walled carbon nanotubes and amorphous silicon thin films

AbstractHybrid heterojunction solar cells based on silicon and single‐walled carbon nanotube (SWCNT) thin films have a simple structure and their manufacture employ simple low‐temperature processes. Moreover, their progress has been rapid during the last decade, wherein the efficiency of heterojunction solar cells combining hydrogenated amorphous silicon (a‐Si:H) and SWCNTs thin film has increased from 0.03% to 8.80%. Here, we present a comprehensive overview of the state‐of‐the‐art on SWCNTs/a‐Si:H heterojunction solar cells. In addition to a comprehensive technology review, important special features such as adhesion of SWCNT film to a‐Si:H, the interface between SWCNT and a‐Si:H, and their influence on the performance of the heterojunctions are included. Future paths for improving the performance of such solar cells are also suggested. Finally, key challenges and trends for further research and development of SWCNTs/amorphous silicon heterojunction solar cells are discussed.This article is categorized under: Photovoltaics &gt; Science and Materials

Solution Processed Organic/Silicon Nanowires Hybrid Heterojunction Solar Cells Using Organosilane Incorporated Poly(3,4-ethylenedioxythiophene):Poly(styrenesulfonate) as Hole Transport Layers.

Hybrid heterojunction solar cells (HHSCs) using crystalline Si nanowires (SiNWs) as the absorber and conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the hole-selective transport layer (HTL) show great potential in both low-cost and high-power conversion efficiency (PCE). However, due to the poor wettability of the PEDOT:PSS solution on SiNWs, conformal coverage of PEDOT:PSS on SiNWs is not easy to achieve. Here, an effective method was developed to decrease the surface tension of the PEDOT:PSS and increase the wettability between PEDOT:PSS and SiNWs by incorporating organosilane into the PEDOT:PSS solution. Two kinds of organosilanes including tetramethoxysilane (TMOS) and vinyltrimethoxysilane (VTMO) were selected as the additives. The surface passivation quality of the SiNWs was dramatically enhanced. The HHSCs utilizing VTMO as the additive show a higher open circuit voltage and higher PCE compared with the TMOS adding ones. By spin-coating Ag nanowires onto the PEDOT:PSS HTL layer and using spin-coated phenyl-C61-butyric acid methyl ester as the electron-selective transport layer, a champion PCE up to 18.12% and a fill factor of 80.1% have been achieved on the full solution processed PEDOT:PSS/n-type SiNWs HHSCs. The findings provide a simple and promising method to achieve high-performance PEDOT:PSS/SiNWs HHSCs.

Role of oxide at interface between organic layer and silicon substrate in hybrid solar cells

Degradation in PEDOT:PSS-silicon hybrid heterojunction solar cells is centered at the organic–silicon interface characterized by an s-shaped JV curve. The effects of interfacial silicon oxide and the degradation of PEDOT:PSS films on solar cell performance were simulated and fit to experimental results and found to be good predictors of JV performance and the development of s-shapes. Transmission line measurement (TLM) studies showed the Ag-PEDOT:PSS interface remains ohmic over 5 weeks and has a contact resistivity < 0.1ohm cm2 over 10 days. X-ray photoelectron spectroscopy (XPS) showed that the interfacial silicon oxide develops rapidly after fabrication with high amounts of suboxide defects that grows and chemically saturates to the native oxide thickness (1.5 nm) and composition as the devices age. Hard X-ray photoelectron spectroscopy (HAXPES) was used to investigate the buried organic–silicon interface and showed that doping in the PEDOT:PSS backbone decreases and the PEDOT:PSS-silicon band alignment does not change measurably as the devices age.

Solution‐Processed Organic/p‐Type Silicon Hybrid Heterojunction Solar Cells

Organic–inorganic hybrid heterojunction solar cells have gained extensive attention due to the simple device structure and low‐cost technological processes, and n‐type silicon has been mainly used as the inorganic absorber in previous research. Herein, hybrid heterojunction solar cells based on p‐type silicon are successfully prepared through a low‐temperature solution method. A preliminary power conversion efficiency over 4% is observed, via optimizing the organic thin‐film deposition and organic/inorganic interface, which enhance the built‐in field and promote the separation of photogenerated carriers in the heterojunction. Therefore, a new idea and possibility are provided for developing low‐cost, high‐performance solar cells.

Efficiency enhancement of Si nanostructure hybrid solar cells by optimizing non-radiative energy transfer from Si quantum dots

Non-radiative energy transfer (NRET) from silicon quantum dots (SiQDs) terminated with ligands is an effective way to improve solar cell efficiency. The NRET effect can be enhanced by minimizing the distance between SiQDs and the solar cell surface. SiQDs were inserted between poly (3,4-ethylene dioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) and Si nanostructures of hybrid heterojunction solar cells. To clarify dependence on ligand length, three different ligands of different lengths were investigated. 1-octene, which has the shortest ligand length, showed the greatest enhancement of NRET, resulting in the highest solar cell efficiency. The non-radiative energy transfer (NRET) effect in Si quantum dots (SiQDs) can be enhanced by shortening the ligand length, resulting in enhanced short circuit current, thus significantly improving the energy conversion efficiency of solar cells. • High-efficiency hybrid solar cells were fabricated by inserting SiQDs into hybrid solar cell with Si nanotips and PEDOT:PSS. • Non-radiative energy transfer from SiQDs terminated with ligands effectively enhanced conversion efficiency of solar cells. • SiQDs with shorter ligands had a higher conversion efficiency. • The highest conversion efficiency of 12.4% was given by hybrid solar cells with 1-octene terminated SiQDs.

High efficient hybrid bulk hetero junction thin-film solar cell embedded with kesterite Cu2ZnSnS4 quantum dots

The photovoltaic performance of kesterite Cu 2 ZnSnS 4 (CZTS) quantum dot (QD) incorporated poly(3-hexylthiophene-2,5-diyl) (Alvarado et al., 1998; Alvarado et al., 1998) [6,6]: phenyl-C61butyric acid hexyl ester (P3HT:PCBH) polymer matrix based organic hybrid heterojunction solar cell configuration is investigated. The inorganic filler material CZTS QDs with P3HT:PCBH matrix, forms double bulk hetero junction (BHJ) throughout in the active layer, which facilitates rapid exciton dissocitaion process at P3HT:PCBH and CZTS:PCBH interfaces that results effective charge carrier separation. The prepared active layer material has been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), Raman and fourier transform infra red (FTIR). The enhanced optical absorbance of prepared hybrid structure has been verified by UV–Visible analysis. It has been observed that the improvement in photo conversion efficiency (PCE) from 2.36% for the solar cell device P3HT:PCBH to 4.12% for CZTS QD based P3HT:PCBH hybrid organic solar cell device. This dramtaic increase in PCE, is mainly due to the significant enhancement in short-circuit current density (J sc ) from 7.6 mA/cm 2 to 11.2 mA/cm 2 . That suggests, the incorporation of p-type kesterite CZTS QDs into P3HT:PCBH polymer matrix enhances the effective exciton dissociation at interfaces resulting charge separation and their fast extraction to electrodes inhibiting e − /h + pair recombination. Furthermore, the hybrid solar cell shows remarkable time stability retaining 80% of original PCE measured after 30 days under ambient environment conditions. The hybrid organic solar cell device shows thermal stability by retaining 95.6% of its intial efficiency measured which has been tested in the temperature range 20–80 °C. • Photovoltaic performance of CZTS QDs:P3HT:PCBH hybrid thin film solar cell is investigated. • PCE of hybrid device has been observed to enhance from 2.36% to 4.12%. • It shows time and thermal stability retaining 80% and 95.6% efficiency.