Heterojunction Photovoltaic Cells Research Articles

Study of the Effect of Exciton Annihilation Lifetime on Some Kinematic and Intrinsic Parameters of a Silicon Heterojunction Solar Cell (HIT), Illuminated by Monochromatic Light

In this article, with a view to improving the efficiency of photovoltaic cells, and given the promising yields of silicon heterojunction photovoltaic cells, we have, using a silicon heterojunction cell (a-Si:H/c-Si) doped with (n+p) , studied the contribution of excitons to the internal quantum efficiency of charge carriers. We then developed a detailed explanation of the energy conversion phenomena, based on an exciton-exciton annihilation process, which allows the electrons of quasiparticles to retain some of their energy. We used a numerical method for solving the charge carrier transport equations and carried out some additional calculations, which enabled us to obtain some results. These results then enabled us to study the influence of the annihilation lifetime on the charge carrier photo-current density, leading to internal charge carrier quantum yields of between 29.29768% and 77.8525%.

Long‐Range Charge Carrier Transport in Planar Polymer Bulk‐Heterojunction Photovoltaic Cells

One‐dimensional scanning optical beam‐induced current (OBIC) measurements have been carried out on polymer bulk heterojunction (BHJ) photovoltaic cells with a planar, or lateral configuration. The planar P3HT:PCBM cells have parallel aluminum or gold electrodes that are 390 to 560 micrometers apart. When a focused laser beam is scanned across the electrode gap, photocurrent or photovoltage is recorded as a function of beam position along with the transmission of the excitation beam. Despite the large electrode gap size, cells with symmetric Al/Al electrodes exhibit significant photocurrent and photovoltage which are the highest at the electrode interfaces and null at the cell center. The OBIC in these large planar polymer BHJ cells is attributed to the metal/BHJ blend Schottky junction. The larger Schottky barrier of the Al/BHJ junction gives rise to a stronger OBIC response than the Au/BHJ junction. The photocurrent and photovoltage always have opposite signs and are antisymmetric about the cell center. In asymmetric Al/Au cells, the electrode work function difference contributes an additional built‐in field/potential drop and significantly modifies the photocurrent and photovoltage profiles. The depletion width of the Al/BHJ Schottky junction is 110–120 μm, while the minority electron diffusion length is determined to be 43.8 μm.

Study of Fabrication Process and Performance Analysis of the CDS/CDTE Based Photovoltaic Cell

Fabrication of CDS/CDTE based heterojunction photovoltaic cell has been undertaken to explore better light conversion efficiency. We have developed a photovoltaic cell using glass coated with Indium doped Tin Oxide (ITO) which works as transparent conducting oxide (TCO). ITO coated glass has promising prospects of enhancing the efficiency of the photovoltaic cell. ITO layers are known to be employed as anode terminal due to the negative polarity they possess compared to the whole PV cell; here, we have employed it for the same function as the front layer. During fabrication of the photovoltaic cell, the deposition of nanoparticles of CDS and CDTE layer is undertaken through doctor-blade method. We have employed pure CDS as window layer for its high band gap of 3.8 eV (particle size: 8 nm) and CDTE as absorber layer due to its high optical absorption coefficient with high mobility, good carrier lifetime and enhanced crystallographic properties. The CDS window layer and CDTE absorber layer together constitute a p-n junction where the CDS window layer captures high intensity photons and transmits the photo-excited electron to CDTE absorber layer, thereby leading to photo-current output, which serves as a base to explore and test its further applications. To obtain band gap of respective CDTE and CDS nanoparticles, optical characterization is used. Silver paste is used as rear contact to form anode terminal having good conductivity and providing better mechanical support to the photovoltaic cell.

Boosting the efficiency up to 33 % for chalcogenide tin mono-sulfide-based heterojunction solar cell using SCAPS simulation technique

In the present article, an FTO/n-ZnO/SnS/Sb2S3/Au heterojunction photovoltaic cell structure was modeled and the cell performance in terms of output parameters viz. open circuit voltage (Voc), short-circuit current density (Jsc), efficiency (η) and fill factor (FF) by varying carrier concentration, and thickness of different layers involved, was studied at ambient conditions. The overall theoretical performance of the designed photovoltaic cell was examined using SCAPS 1-D simulation programme. The simulation programme operates by resolving semiconductor equations such as the Poisson equation, drift-diffusion equation, and continuity equation for both electrons and holes. The equations are generally solved in one-dimension (1D) in a steady state condition. The role of Sb2S3 HTL on the performance study of tin sulfide chalcogenide-based heterojunction photovoltaic cell (HPVC) was also analyzed. Moreover, the impact of functioning temperature between 273 K and 350 K on the performance of photovoltaic cell was observed, and an increase in temperature resulted in poor performance. The impact of different metal back contact work functions and some more electrical parameters viz. series-shunt resistances, defect concentration of layers and interfaces, and radiative recombination coefficients were also observed on HPVC. The simulation results revealed that the HTL Sb2S3 forms proper band alignment with the SnS chalcogenide absorber layer and enhanced the efficiency, η of HPVC by lessening the carrier recombination at the rear contact side. The dislocation and interface defect reduced significantly which leads to the smooth conduction of hole carriers, therefore, preventing of minority carriers to recombine within the absorber. A significant increase in the efficiency ∼33.24 % together with performance cell parameters Jsc ∼34.38 mA/cm2, Voc ∼1.09 V, and FF ∼88.49 % was observed.

Improving the efficiency of a CIGS solar cell to above 31% with Sb2S3 as a new BSF: a numerical simulation approach by SCAPS-1D.

The remarkable performance of copper indium gallium selenide (CIGS)-based double heterojunction (DH) photovoltaic cells is presented in this work. To increase all photovoltaic performance parameters, in this investigation, a novel solar cell structure (FTO/SnS2/CIGS/Sb2S3/Ni) is explored by utilizing the SCAPS-1D simulation software. Thicknesses of the buffer, absorber and back surface field (BSF) layers, acceptor density, defect density, capacitance-voltage (C-V), interface defect density, rates of generation and recombination, operating temperature, current density, and quantum efficiency have been investigated for the proposed solar devices with and without BSF. The presence of the BSF layer significantly influences the device's performance parameters including short-circuit current (Jsc), open-circuit voltage (Voc), fill factor (FF), and power conversion efficiency (PCE). After optimization, the simulation results of a conventional CIGS cell (FTO/SnS2/CIGS/Ni) have shown a PCE of 22.14% with Voc of 0.91 V, Jsc of 28.21 mA cm-2, and FF of 86.31. Conversely, the PCE is improved to 31.15% with Voc of 1.08 V, Jsc of 33.75 mA cm-2, and FF of 88.50 by introducing the Sb2S3 BSF in the structure of FTO/SnS2/CIGS/Sb2S3/Ni. These findings of the proposed CIGS-based double heterojunction (DH) solar cells offer an innovative method for realization of high-efficiency solar cells that are more promising than the previously reported traditional designs.

A comparison between the mainstream heterojunction PV studies

Among the wide range of third-generation photovoltaic power generation technologies, there is a widely used type of photovoltaic - heterojunction photovoltaic cells. Although each of the different types of heterojunction photovoltaics has been studied in depth, no one has considered the direct application of the different types of heterojunction photovoltaics at the application level. This paper introduces the composition and advantages of heterojunction photovoltaic cells, and briefly introduces graphene/n-type amorphous silicon heterojunction photovoltaic, organic compound/inorganic heterojunction photovoltaic, and inorganic/inorganic heterojunction photovoltaic represented by CuO and Zn2O, and summarizes the different photovoltaic conversion efficiencies, preparation methods, and other key information of these cells, and compares these information. In particular, whether the photovoltaic conversion efficiency can reach the shockley-queisser limit is examined. Among them, the photoconversion efficiency of graphene/n-type amorphous silicon heterojunction and simple metal oxide heterojunction was not very satisfactory, and finally the heterojunction PV cell constructed by the byorganic cavity-conducting material led by Graezel et al. was chosen among the different research directions of organic/inorganic heterojunction PV cells. Cavity-conducting material combined with a titanium dioxide nanofilm with adsorbed dye as a relatively ideal heterojunction PV cell for comparison was examined in this paper, which provides a proposal for the commercial development of new heterojunction PV cells in the future.

Performance of Sb2Se3‐Based Solar Cell: With and Without a Back Surface Field Layer

Optimizing thin‐film‐based solar cells’ efficiency is essential for expanding renewable energy deployment. Fundamental device properties such as life‐span and optical properties must be enhanced simultaneously to reduce recombination and losses. Herein, the design and numerical study of an efficient Sb2Se3‐based dual heterojunction (n‐ZnSe/p‐Sb2Se3/p+‐MoSe2) photovoltaic cell with the help of SCAPS‐1D simulation software by using the physical parameters of various layers are presented. The thickness and doping of each layer are considered during the optimization of the device. The work functions of back and front contact also affect the overall performance. Defects in each layer and interface defects are highly responsible for the increment in series resistance. Thus, these defects are also studied. The efficiency improved significantly from 22.52% to 24.57% when MoSe2 is used as a back surface field (BSF) layer. The results demonstrate that the addition of BSF significantly increased the open‐circuit voltage, short‐circuit current density, and fill factor, all of which are within the Shockley–Queisser limits of a dual heterojunction solar cell. This study indicates the possibility of producing highly efficient Sb2Se3 heterojunction‐based solar cells.

Computational Study of New Small Molecules based Thiophene as Donor Materials for Bulk Heterojunction Photovoltaic Cells.

In this research work, we study the structural, optical, electronic, and photovoltaic properties of eight thiophene-based π-conjugated organic molecules using quantum methods namely time-dependent density functional theory. In particular, we identify the relationships between the chemical structure of these π-conjugated organic molecules and their optoelectronic properties. Moreover, we calculate and compare the highest energy occupied molecular orbital and lowest energy unoccupied molecular orbital energy levels of these compounds which act as donor with the ones of the acceptorphenyl-C61-butyric acid methyl ester. As a result, the investigated molecules show a low band gap, suitable open-circuit voltage and appropriate alignment energy level between the engineered donor molecules and the acceptor phenyl-C61-butyric acid methyl ester. This theoretical study shows that these new molecules have potential properties for the development of organic heterojunction photovoltaic cells.

Study of a new composite based on SnO2 nanoparticles — P3HT:PC71BM co-polymer blend, used as potential absorber in bulk heterojunction photovoltaic cells

The properties of a novel P3HT:PC 71 BM:SnO 2 -nanoparticles (NPs) composite, used as potential absorber for Organic Photovoltaic Cells (OPCs), were investigated. The structural, morphological and optical characterizations of this composite demonstrated an enhancement of the ITO/PEDOT:PSS/P3HT:PC 71 BM: SnO 2 -NPs/LiF/Al ternary structure when compared to the ITO/PEDOT:PSS/ P3HT:PC 71 BM/LiF/Al binary one. This behavior is due, on one hand to the fact that SnO 2 -NPs behave as a secondary non-fullerene acceptor, and on the other hand to the superior electrical conductivity of the SnO 2 -NPs, very well dispersed in the polymeric blend as compared to other nanostructured inorganic materials. These properties led to a better photogeneration and transport of charge carriers, decreasing the series resistance, increasing the fill factor, and consequently the cell’s efficiency, too. The incorporation of NPs into ternary OPCs could represent a way to enhance their performances by improving the photogeneration of charge carriers, as well as their transport and collection to the electrodes. • Solar cells based on ternary P3HT:PC 71 BM:SnO 2 -nanoparticles compound were fabricated. • SnO 2 -nanoparticles addition allowed an extended absorption spectra at shorter wavelengths. • EQE increased by 50% in the 400-450 nm range, when compared to the binary system. • Current–voltage characteristics of the photovoltaic element revealed improved parameters.

Improved performance of PCBM/MAPbI3 heterojunction photovoltaic cells with the treatment of a saturated BCP/IPA solution

The interfacial contact quality between the hydrophilic MAPbI 3 and hydrophobic PCBM thin films are improved by using the treatment of a saturated bathocuproine/isopropanol (BCP/IPA) solution, which largely increases the power conversion efficiency (PCE) from 12.96% to 18.67%. The atomic force microscopic images, water-droplet contact angle images, viscosity measurement results and near-infrared transmittance spectra show that the increased open-circuit voltage (V OC ) is related to the formation of a denser PCBM thin film and the better contact quality of the PCBM/MAPbI 3 heterojunction. Besides, the power-dependent current density-voltage (J-V) curves show that the lower defect density in the solar cells results in the higher V OC . In other words, the treatment of a saturated BCP/IPA solution can decrease the defect density of the PCBM/MAPbI 3 heterojunction and thereby boosting the photovoltaic performance and extending the device lifespan. • The saturated BCP/IPA solution treatment increases the density of the PCBM thin film. • The saturated BCP/IPA solution treatment strengthens the contact quality at PCBM/MAPbI 3 interface. • The saturated BCP/IPA solution treatment increases the hydrophobicity of PCBM/MAPbI 3 heterojunction. • The saturated BCP/IPA solution treatment improves the PCE of photovoltaic cells from 12.69% to 18.67%.

A Review On Chemical Bath Deposition Mediated Synthesis Of Binary/Ternary Photoconductive Metal Sulfide Thin Films

Photoconductors are normally composed of semiconductors, which show an enhancement in the electrical conductivity due to the absorption of photons. Among the binary compounds PbS, ZnS, and CdS are the most typical inorganic semiconductor materials owing to their band structure. The properties of Zn1-xCdxS thin films lie in between the properties of ZnS and CdS, widely used as a wide band gap window material in heterojunction photovoltaic solar cells and in photoconductive device. Some ternary compounds based on CdS and PbS has been formed such as PbS with some percentage of Cd(CdxPb1-XS), and it has been observed by optical measurement that that the band gap value of this ternary compounds varies with x. In this review paper, we will emphasis the fabrication of thin film of binary and ternary metal-sulphide compounds by chemical bath deposition method.

N-Si/p-Sb2Se3 structure based simple solar cell device

Sb2Se3 is a p-type semiconductor that has been widely used as an absorber layer in thin film solar cells. For this study, Sb2Se3 was made using the solid-state reaction route, and thin films were deposited by the thermal evaporation method at room temperature and annealed at various temperatures. The crystallinity of Sb2Se3 thin films improved after annealing. The material and thin films were characterized by XRD, Raman, SEM, and UV–Vis spectroscopy to study their structural and optical properties. A simple device structure that can be made using a thermal evaporation system is proposed. We have accomplished simulation work based on Sb2Se3/c-Si hetero-junction photovoltaic cells using SCAPS-1D. In the simulation, experimental data of Sb2Se3, including its band gap, thickness, and absorption coefficient, have been introduced. The simulation is used to extract the parameters, such as back contact work function, electron affinity, and the thickness of the p-Sb2Se3 layer and n-Si layer, which is also varied and optimized to improve the device's performance. p-Sb2Se3 with a band gap of 1.64 eV showed a maximum efficiency of 12.75% at the optimized conditions. As n-Si is commercially available, this simple device structure can have multiple local applications. It can be considered a reliable method for predicting photovoltaic performance for future studies, such as improving the efficiency of Sb2Se3 solar cells or trying out a new tandem solar cell structure using Sb2Se3.

Optimization of electrical properties for performance analysis of p-Si/n-CdS/ITO heterojunction photovoltaic cell

There is always a photogenerated current in solar photovoltaics because of the movement of charge carriers in the photovoltaic device. Therefore, it is necessary and exciting to explore its electrical properties. Thus, in the present communication, the electrical properties (as electron/hole mobilities, the effect of electron affinity, series/shunt resistance, etc.) have been optimized for p-Si photovoltaic cells with thin n-CdS emitter and ITO window layer. In this context, the signature of charge carrier mobilities on the performance of the proposed configuration, i.e., the hole mobility of the p-Si (p-type Crystalline Silicon) absorber layer and the electron mobility of the n-CdS (n-type Cadmium Sulphide) emitter/buffer layer has been optimized. Under the variation in hole mobility from 50 cm2/Vs to 500 cm2/Vs and the electron mobility from 10 cm2/Vs to 100 cm2/Vs simultaneously, the observed 2D contour plots reveal the effective change in power conversion efficiency from 17.72 % to 18.25 %. Moreover, the effect of electrical parameters, i.e., series and shunt resistance, on the characteristic performance parameters such as power conversion efficiency (η), open-circuit voltage (Voc), short circuit current density (Jsc), and fill factor (FF). An increase in series resistance (0 Ωcm2 to 10 Ωcm2) deteriorates the performance of the proposed solar cell considerably (19.66% to 8.87%). Further, the effect of the electron affinity of the p-Si absorber layer on fill factor and open circuit voltage is observed.

Investigation of Electrical Parameters of CdTe Photovoltaic Devices by Computational Analysis

This article discusses the numerical analysis of heterojunction photovoltaic cells based on cadmium telluride (CdTe) using the SCAPS‐1D software. A novel glass/FTO/SnO2/CdS/interdiffusion/CdTe/SnS2/Se photovoltaic cell design is proposed for investigation. Additionally, the effect of thickness variation in the p‐type CdTe film, thickness variation in the interdiffusion layer, defect density in the CdTe film, defect density in the interdiffusion layer, and acceptor concentration in the CdTe layer is studied in order to improve the photovoltaic cell's efficiency. The study determines an optimal thickness of 1 and 0.6 μm for the CdTe and interdiffusion layers, respectively, a defect density of 1 × 1014 cm−3 for the CdTe film and interdiffusion region, an interface defect density of 1 × 1010 cm−3 between CdTe/interdiffusion, SnS2/CdTe, and CdS/interdiffusion, and an acceptor concentration value of 8.5 × 1015 cm−3. The optimized CdTe photovoltaic cell structure with current density (Jsc) = 30.003 mA cm−2, open‐circuit voltage (Voc) = 1.061 V, and fill factor (FF) = 88.10% achieves a 28.07% efficiency, compared to the baseline CdTe photovoltaic cell structure with a 23.01% efficiency.

Laser-induced graphene electrode based flexible heterojunction photovoltaic cells

Graphene based nanomaterials have attracted significant research interest due to their unique optoelectronic properties which can be tuned to tailor the functionalization in various photovoltaic (PV) applications. These PVs are capable of powering various wearable and flexible electronic devices such as touch-panels, light-emitting diodes (LEDs), sensors, high speed field effect transistors (FETs), etc., which can be a low-cost alternative to traditionally employed silicon solar cells. However, in terms of processing performance and electrical properties, current methods of manufacturing graphene-based PVs have numerous drawbacks. Therefore, there is a need for more effective fabrication methods with commercial feasibility and roll-to-roll processing of graphene-based PVs. This article is the first to present a laser-based patterning technique for fabricating graphene electrodes from polyimide that are compatible with flexible and thermally sensitive substrates for solar cell applications. A heterojunction PV, with ferroelectric Cr-doped BiFeO3 (BFCrO), was deposited on the flexible graphene as the energy harvesting layer sandwiched between p-NiO and n-WS2 window layers. Subsequently, its PV performance was compared with the similar multi-junction PV built on the Indium‑tin Oxide (ITO) one. The LIG electrode outperformed the ITO with its excellent stability, flexibility, and conductivity. The maximum power conversion efficiency (PCE) culminated was 5.20% which is around 5 folds enhancement when compared to the ITO based PV. Furthermore, after bending graphene electrode to 130°, the sheet resistance returned to its original value, while the resistance of ITO increased due to the cracking effect. With these unique properties, LIG electrodes can be promising for the development of flexible ferroelectric BFO based heterojunction PV devices.

New BODIPY derivatives with triarylamine and truxene substituents as donors for organic bulk heterojunction photovoltaic cells

We have designed two new BODIPY derivatives, denoted as 6a and 6b, substituted with truxene moiety and triphenylamine (TPA) unit groups and have investigated their optical and electrochemical properties. Dyes 6a and 6b were employed as donor along with PC71BM or Y6 as acceptor for the fabrication of binary and ternary organic solar cells. After optimization of the binary and ternary active layers, we have achieved over all power conversion efficiency (PCE) of 11.37 % and 13.32% for 6a:PC71BM:Y6 and 6b:PC71BM:Y6 ternary organic solar cells, respectively, which are higher than the binary organic solar cells based on PC71BM or Y6 acceptor. The higher power conversion efficiency for ternary OSC is possibly attributed to the better exciton generation rate, exciton dissociation and charge collection.

Formation and Characterization of Ge1–x–ySixSny/Ge Heterojunction Structures for Photovoltaic Cell Application

Group-IV alloy semiconductor materials are much attractive for photovoltaic application, as those realizes multijunction photovoltaic with multi-heterostructure like group-III-V compound semiconductors [1]. In addition, group-IV alloy materials are expected to be familiar to Si integrated electronics. Ge1–x–ySixSny is one of candidate materials suitable for multijunction photovoltaic, since ternary alloy semiconductor provides energy band design independent on the lattice constant. The energy band gap of Ge1–x–ySixSny can be controlled from 0.66 eV to 1.0 eV with the epitaxial layer whose lattice is matching to Ge substrate.We previously reported the epitaxial growth of Ge1–x–ySixSny layers and also investigated the crystalline and electronic properties of them [2, 3]. However, the junction properties of Ge1–x–ySixSny/Ge heterostructure have not been well understood and it is necessary to clarify the crystalline and electronic properties of group-IV ternary alloy hetero junctions. In this study, we examined the crystal growth of pseudomorphic epitaxial layers of Ge1–x–ySixSny ternary alloy on Ge(001) substrates to form heterojunction structure for photovoltaic application. We also investigated the electronic and optoelectronic properties of these Ge1–x–ySixSny/n-Ge heterojunction diodes.Substrate used was n-type Ge(001) wafer. After chemical cleaning of substrate, a 200 nm-thick undoped Ge1–x–ySixSny layer was grown at 150–350 °C on substrate using molecular beam epitaxy system in ultrahigh vacuum chamber. Ge and Sn were deposited using Knudsen cells and Si was done using electron gun evaporation. Then, we prepared a mesa-shaped structure with wet etching. A 300 nm-thick SiO2 layer was deposited with coating of spin-on-glass and annealing at 450 °C. Finally, an Al electrode was prepared on contact holes to form heterojunction diode structure.We confirmed the crystalline structure of epitaxial layers with X-ray diffraction reciprocal space mapping. A Ge1–x–ySixSny layer with a high Sn content of 12% can be prepared with lattice matching epitaxy on Ge at a low temperature below 250 °C. It is also found that the small misfit between Ge1–x–ySixSny and Ge effectively impacts on the high crystalline quality and high thermal stability of substitutional Sn atoms in Ge matrix.Absorption spectroscopy and current-voltage characteristics of undoped Ge1–x–ySixSny/n-Ge heterojunction diodes were also performed. We observed good rectifying property of the diodes meaning that the majority carrier of these undoped Ge1–x–ySixSny ternary alloy layers is hole unintentionally generated due to defects. We also found the extension of the energy band gap of Ge1–x–ySixSny layer with Si and Sn contents. Photovoltaic property of Ge1–x–ySixSny/Ge heterojunction diodes were also measured. We can see the increasing of the open circuit voltage, Voc from 0.08 to 0.12 V for undoped Ge/n-Ge to undoped Ge0.54Si0.36Sn0.10/Ge heterojunction photovoltaic cell structure, which indicates the enhancement of Voc with increasing the energy bandgap of epitaxial layer. We also achieved the improvement of Voc by 0.14 V with 500 °C-annealing in hydrogen (H2) ambient, which suggests the annihilation or termination of point defect in the heterojunction structure.In conclusions, heterojunction structure with Ge1–x–ySixSny ternary alloy semiconductor layer provides the energy band engineering for photovoltaic applications. Understanding and controlling the defect properties in epitaxial growth and heterojunction formation should be key factors for the enhancement of performance of group-IV multijunction photovoltaic.

Formation and Characterization of Ge1–x–ySixSny/Ge Heterojunction Structures for Photovoltaic Cell Application

We have examined the epitaxial growth of Ge1−x−y Si x Sn y ternary-alloy layer on Ge(001) substrates for photovoltaic application. We have investigated the electronic and optoelectronic properties of Ge1−x−y Si x Sn y /n-Ge heterojunction structure. A pseudomorphic Ge1−x−y Si x Sn y layer with good crystallinity and a high Sn content of 12% can be prepared on Ge substrate with a low temperature growth at 200ºC. We have also demonstrated engineering the absorption energy and the photovoltaic characteristics of undoped Ge1−x−y Si x Sn y /n-Ge heterojunction photovoltaic cell. We have examined the epitaxial growth of Ge1−x−y Si x Sn y ternary-alloy layer on Ge(001) substrates for photovoltaic application. We have investigated the electronic and optoelectronic properties of Ge1−x−y Si x Sn y /n-Ge heterojunction structure. A pseudomorphic Ge1−x−y Si x Sn y layer with good crystallinity and a high Sn content of 12% can be prepared on Ge substrate with a low temperature growth at 200ºC. We have also demonstrated engineering the absorption energy and the photovoltaic characteristics of undoped Ge1−x−y Si x Sn y /n-Ge heterojunction photovoltaic cell.

Preparation and optimization of heterojunction donor(DLC) – acceptor(SI) as a solar cell by DFT and PLD

Hybrid bilayer heterojunction (DLC) thin-film P-type as an active donor layer and (Si) thin-film n-type as an acceptor with (Electron Transport Layer ), were fabricated using Qswitching Nd-YAG Pulsed Laser Deposition (PLD) method under vacuum condition 10-3 torr on two electrodes for (AL) Aluminum material is used to construct the hydride bilayer heterojunction photovoltaic solar cell (PVSC). The electrical properties of hybrid heterojunction Al / DLC / SI / AL thin film were studied. The result showed the voltage of open circuit (Vm=0.145V ), a short circuit (Jm=9.3mA/cm2 ), and the fill factor (FF) of (0.4709), with Xenon lamp with an intensity (235mw/cm2 ), the conversion efficiency (η=3.54%) at thickness(75nm). While the theoretical calculations and optimization of the HETEROJUNCTION confirmed the possibility of using it as a successful solar cell, the calculation of the small energy gap and thus the high electrical conductivity, and the determination of the type of charge carriers(p), as well as some electronic properties such as electrostatic potential surfaces and 3-D electron density, hardness, softness and electrophilicity, were clarified.

Efficient and thermally stable BHJ solar cells based on a soluble hydroxy-functionalized regioregular polydodecylthiophene

A new regioregular polythiophene derivative, called poly[3-(12-hydroxydodecyl)thiophene] (PT12OH), was synthesized by post-functionalizing its ω-brominated precursor poly[3-(12-bromododecyl)thiophene] (PT12Br) prepared using the Grignard metathesis route. Thanks to the optimal balance between hydrophilic and hydrophobic groups within its structure, PT12OH was highly soluble and easily filmable from common organic solvents allowing for its complete characterization. It also showed enhanced thermal properties, crystallinity, and self-assembling capabilities by the formation of strong inter- and intrachain hydrogen bonds. Bulk heterojunction photovoltaic cells with PT12OH and PC61BM showed a PCE of 4.83% and a remarkable over-time stability, offering good photoconversion efficiency even after 120 h of accelerated aging. Indeed, the PCE decrease was 34% for the hydroxylated polymer and 65% for its brominated precursor. It should also be pointed out that the enhanced thermal stability of PT12OH was achieved without resorting to any complex post-annealing photochemical, thermal, or chemical treatment and was thus directly ascribable to the polymer chemical structure. The simple and effective synthetic procedure, photovoltaic efficiency, and enhanced stability revealed the potential of PT12OH for large-scale organic solar cell applications.