Ag Solar Cell Research Articles

Impact of 1,8-Diiodooctane (DIO) Additive on the Active Layer Properties of Cu2ZnSnS4 Kesterite Thin Films Prepared by Electrochemical Deposition for Photovoltaic Applications

Kesterite Cu2ZnSnS4 (CZTS) thin films using various 1,8-diiodooctane (DIO) polymer additive concentrations were fabricated by the electrochemical deposition method. The optical, electrical, morphological, and structural properties of the CZTS thin films synthesized using different concentrations of 5 mg/mL, 10 mg/mL, 15 mg/mL, and 20 mg/mL were investigated using different techniques. Cyclic voltammetry exhibited three cathodic peaks at -0.15 V, -0.54 V, and -0.73 V, corresponding to the reduction of Cu2+, Sn2+, Sn2+, and Zn2+ metal ions, respectively. The analysis of the X-ray diffraction (XRD) pattern indicated the formation of the pure kesterite crystal structure, and the Raman spectra showed pure CZTS with the A1 mode of vibration. Field emission scanning electron microscopy (FE-SEM) indicated that the films are well grown, with compact, crack-free, and uniform deposition and a grain size of approximately 4 µm. For sample DIO-20 mg/mL, the elemental composition of the CZTS thin film was modified to Cu:Zn:Sn: and S = 24.2:13.3:12.3:50.2, which indicates a zinc-rich and copper-poor composition. The X-ray photoelectron spectroscopy (XPS) results confirmed the existence of Cu, Sn, Zn, and S elements and revealed the element oxidation states. The electrochemical deposition synthesis increased the absorption of the CZTS film to more than 104 cm-1 with a band gap between 1.62 eV and 1.51 eV. Finally, the photovoltaic properties of glass/CZTS/CdS/n-ZnO/aluminum-doped zinc oxide (AZO)/Ag solar cells were investigated. The best-performing photovoltaic device, with a DIO concentration of 20 mg/mL, had a short-circuit current density of 16.44 mA/cm2, an open-circuit voltage of 0.465 V, and a fill factor of 64.3%, providing a conversion efficiency of 4.82%.

AFORS-HET simulation for investigating the performance of ZnO/n-CdS/p-CdTe /Ag solar cell depending on CdTe acceptor concentration and temperature

In this study, a single junction dc photovoltaic solar cell simulation was carried out. ZnO/n-CdS/p-CdTe/Ag cell properties were investigated through the recognized ‘Automatic Heterostructure Simulation (AFORS-HET)'. In the theoretical simulation process, the temperature was between 200 K and 400 K and the acceptor concentration of the CdTe layer was in the range of 1014 cm−3-1019 cm−3. The variation of Voc (open circuit voltage), Jsc (short circuit current density), FF (filling factor) and η (efficiency) values with T (temperature) and Na (acceptor concentration) were investigated. It was observed that as Na increased, Voc values increased and Jsc values decreased. Voc, FF and η decreased as the temperature was increased. Also, the sensitivity of FF to Na increased for acceptor concentration values greater than 1018 cm−3. It has been also shown that the filling factor decreased with photovoltaic current. ZnO/n-CdS/p-CdTe/Ag cells with an acceptor concentration greater than 1018 cm−3 exhibited high efficiency for all studied temperatures.

The effect of sodium (Na) doping on the performance of n-Si/Cu2SnS3 heterojunction solar cells deposited by PLD using a homemade target.

n-Si/Cu2SnS3(CTS) heterojunction solar cell has been fabricated in this work using different doping concentration of Na into CTS thin films. The pure raw powders of Copper, Tin, Sulphur and NaF have been ball milled, pressed and heated to form CTS pure and Na doped targets. The deposition of CTS thin film pure beside 1%, 3% and 5% Na doped CTS thin film have been held by pulsed laser deposition technique. The different properties of CTS thin films have been studied using different analyse methods and it has been observed that the properties of these CTS thin films are strongly dependent on Na concentration. Doping CTS thin films with 1% Na has enhanced the crystallinity and the optical absorption. The solar cells based on n-Si/p-CTS heterojunction present different power conversion efficiency according to Na concentration in CTS thin films. The best photovoltaic performance has been obtainable by Al/n-Si/CTS(1%Na doped)/Ag solar cell with open circuit voltage of 300 mV and power conversion efficiency of 1.02%.

Heterostructure Silicon Solar Cells with Enhanced Power Conversion Efficiency Based on Si x /Ni3+ Self-Doped NiO x Passivating Contact.

Developing efficient crystalline silicon/wide-band gap metal-oxide thin-film heterostructure junction-based crystalline silicon (c-Si) solar cells has been an attractive alternative to the silicon thin film-based counterparts. Herein, nickel oxide thin films are introduced as the hole-selective layer for c-Si solar cells and prepared using the reactive sputtering technique with the target of metallic nickel. An optimal Ni3+ self-doped NiOx film is obtained by tuning the reactive oxygen atmosphere to construct the optimized c-Si/NiOx heterostructure band alignment. A thin SiOx interlayer was further introduced to reduce the defect of the c-Si/NiOx interface with the UV–ozone (UVO) treatment. The constructed p-type c-Si/SiOx/NiOx/Ag solar cell exhibits an increase in the open voltage from 586 to 611 mV and achieves a 19.2% conversion efficiency.

Photovoltaic behavior of SnS solar cells under temperature variations

The present study investigates the origin of the temperature dependency of the photovoltaic behavior associated with FTO/TiO2/SnS/Ag solar cells. This research is conducted using photoluminescence (PL) spectroscopy at a temperature range of 25–85 °C. Tin sulfide (SnS) solar cells are fabricated from the SnS nanostructure via the co-precipitation method. SnS solar cells are deposited using the spin coating process and characterized at a working temperature. Optical results confirm the effect of temperature on the defects and changes in the band gap of solar cells. Photovoltaic results also show that the increase in temperature reduces cell performance. The temperature dependency of cells is assessed and moderated by adding the CdS layer on the TiO2/SnS interface, and an improvement is observed in the solar cell parameters.

Symmetric strain- and temperature-dependent optoelectronics performance of TiO2/SnS/Ag solar cells

Working temperature-dependent photovoltaic and optoelectronic properties of FTO/TiO2/SnS/Ag solar cell are presented using the Raman spectroscopy and electrical characterizations. Nanostructured SnS thin film is deposited using a green binder by the spin coating method. The effect of addition of the CdS layer is also investigated on the temperature-dependence of the mentioned properties. Raman results indicate that addition of the CdS layer increases the induced strain on the solar cell. An increase in the working temperature decreases the photovoltaic performances of solar cells due to different factors. Mobility (μh) and trap-filled limit voltage (VTFL) of solar cells are increased and decreased by increasing the temperature, respectively. Finally, the results obtained in this study demonstrate the key role of the working temperature in the photovoltaic and optoelectronic behavior of the SnS solar cell, which can be used to understand this behavior in the other third generation of solar cell materials.

Design of high performance and low resistive loss graphene solar cells

Despite metallic plasmonic excitations can enhance the performance of ultra-thin solar cells however these so-called plasmonic solar cells suffer from a large resistive (Ohmic) loss caused by metallic elements. In this work, we report on a new design that uses graphene nanoribbons (GNRs) in a two-dimensional (2D) grating form at the top of the semiconductor-on-insulator (SOI) solar cells aimed to reduce the resistive loss. The results showed that GNRs can remarkably reduce the resistive loss compared to the SOI cell with Ag nanograting, while keeping all other cell’s parameters, comparable with those of Ag SOI cell. Optical absorption and short-circuit current density of the graphene cells showed, respectively, enhancements of 18 and 1.7 times when optimizations were done with respect to width and the grating period. Our calculations showed that the graphene solar cells dissipate at most 5% of incident sunlight power as narrow and tiny peaks around 508 nm, which is noticeably lower than those of Ag solar cells with high and broad band peaks with the maximum values of 29% at 480 nm and 24% at 637 nm.

An improvement on the conversion efficiency of Si/CZTS solar cells by LSPR effect of embedded plasmonic Au nanoparticles

In this work, Au/Si/CZTS/Ag and Au/Si/plasmonic-CZTS/Ag solar cells have been produced using PLD technique. These CZTS solar cells have been produced based on p-type CZTS ultrathin films at different thicknesses of 61 nm, 112 nm and 210 nm which were grown on an n-type Si wafer. Morphologic and crystalline structures as well as optical characteristics of CZTS ultrathin films have been investigated by courtesy of AFM, XRD and UV–vis spectra. J-V characteristics of CZTS solar cells have been obtained under AM 1.5 solar radiation of 80 mW/cm2. It has been observed that Jsc, Voc and η values of CZTS solar cells increase as thickness of CZTS ultrathin films are diagnosed to an optimum thickness. But, CZTS ultrathin films at thickness of 61 nm and 112 nm have low absorption rate and it was observed that absorption rate of CZTS ultrathin films increase dramatically in visible and NIR regions after Au plasmonic nanoparticles were embedded in these CZTS ultrathin films. Furthermore, Jsc and η values of plasmonic CZTS solar cells increase and that increase can be attributed to the transfer of electrons from the plasmonic Au NPs to the conduction band of CZTS semiconductor, the photon absorption of CZTS ultrathin films from visible to NIR region in the wide spectral region, and the increase in the path length of light through in CZTS semiconductor by photon scattering of Au nanoparticles.

Cd2SnO4/CdS/Cu2O/Ag solar cell obtained by chemical techniques

By first time Cd2SnO4/CdS/Cu2O/Ag heterojunctions were studied for their application in solar cells. The heterostructure was deposited on glass-substrate and obtained by chemical techniques: i) Cd2SnO4 as TCO by sol-gel, ii) CdS as n-layer by chemical bath deposition and iii) Cu2O as p-layer by spray pyrolysis. The thicknesses of the Cd2SnO4 and CdS layers were 290 nm and 135 nm, respectively. Different thicknesses of Cu2O (τ) were used to study the effect of this parameter on the solar cell performance (135, 185, 220, 350 and 800 nm). The best photovoltaic parameters were obtained with τ=220 nm achieving an VOC = 346 mV, JSC = 1.57 mA/cm2, FF = 33.4 and η = 0.18%. External quantum efficiency shows current generated at energy values below Cu2O and CdS band gaps. This contribution of current is mainly attributed to defects in the Cu2O lattice that result in a source of energy levels within the band gap.

Production and photovoltaic characterisation of n-Si/p-CZTS heterojunction solar cells based on a CZTS ultrathin active layers

In this study, Au/n-Si/p-CZTS/Ag solar cells have been produced by using PLD technique. Ultrathin CZTS films have been grown on n-Si wafer in different thicknesses depending on number of laser pulses. These ultrathin CZTS films were analysed by XRD, AFM and UV–vis spectra. J–V characteristics of Au/n-Si/p-CZTS/Ag solar cells have been determined based on thickness of ultrathin CZTS films under AM 1.5 solar radiation of 80 mW/cm2. Short circuit current density (mA/cm2), fill factor, open circuit voltage (V) and power conversion efficiency (%) of ultrathin CZTS film solar cells have been determined for device produced in this work. The photovoltaic (PV) characteristics of ultrathin CZTS film solar cells has been discussed in detail in this present article and, as a result, the ideal ultrathin CZTS film solar cell structure having the highest efficiency has been determined and concluded.

Large area MoS2/Si heterojunction-based solar cell through sol-gel method

Large area MoS2/Si heterojunction-based solar cell was prepared in which MoS2 thin film was directly grown on p-Si wafer using sol-gel method. Chemical bonding and microstructure analysis show that the MoS2 film was in the initial region of transition from amorphous to microcrystalline phase. Compared with the ITO/p-Si/Ag structure without MoS2, the open-circuit voltage (VOC), short-circuit current density (JSC) and fill factor (FF) of the ITO/MoS2/p-Si/Ag solar cell were improved dramatically, and the conversion efficiency (CE) increased from 1.1% to 4.6%. The insertion of MoS2 film reduced the interface defects concentration and increased the depletion region width of the solar cell, showing its enhancement effect on both chemical passivation and field passivation.

Synthesis and characterization of CdS window layers for PbS thin film solar cells

Window layers, cadmium sulfide (CdS) thin films were synthesized on tin doped indium oxide coated glass substrates (ITO) with two different temperatures of 85 °C and 90 °C and ammonium hydroxide concentration of 1 M and 9.96 M, respectively via the chemical bath deposition (CBD) method, while absorption layers, lead sulfide (PbS) thin film were deposited on ITO substrates at room temperature using the successive ionic layer absorption and reaction (SILAR) technique. Then, these layers were integrated in ITO/CdS/PbS/Ag solar cell structures. The structural, morphological and optical properties of the thin films as well as electrical properties of the solar cells were investigated. X-ray diffraction studies showed that the CdS thin films have hezagonal structure while PbS thin films have cubic structure. The photovoltaic performance of the solar cells showed that the solar cell fabricated with CdS film deposited at 90 °C exhibited higher efficiency (η) of 4.85% including JSC = 12.44 mA cm−2, VOC = 1 V, FF = 0.39 than the CdS film deposited at 85 °C (η = 3.59%, JSC = 9.43 mA cm−2, VOC = 1 V, FF = 0.38. These results reveal that the crystal structure, surface morphology and optical properties of CdS thin film have a significiant effect on device performance and the solar cell fabricated using CdS film deposited at 90 °C shows better photovoltaic performance.

Thin film solar cells with extremely thin absorber layer having multiple absorption bands: A novel attempt

Chemical Spray Pyrolysis (CSP) technique was utilized for depositing ‘Extremely Thin Absorber (ETA)’ layer solar cells having phases of both CuInS2 and Cu2S in the absorber, so as to have multiple band gaps of 1.45eV and 1.80eV respectively. Cell fabricated using this absorber is almost equivalent to a tandem cell capable of absorbing photons of two energies. This was achieved simply by lowering concentration of indium in conventional CuInS2. Presence of both CuInS2 and Cu2S phases were confirmed through X-ray diffraction and Raman studies. Multiple absorptions in the film were evident from the absorption spectra. Also the ‘CuInS2:Cu2S’ absorber was used for the fabrication of ETA solar cell with structure ITO/(CuInS2:Cu2S)/In2S3/Ag. Comparing with performance of ITO/CuInS2/In2S3/Ag solar cells, they exhibits 17%, 15% and 47% increases in short circuit current, fill factor and efficiency respectively. The best device realized in this study has open circuit voltage of 518mV and short circuit current density of 14.25mA/cm2. Efficiency and fill factor were 3.82% and 52% respectively.

Effect of rapid thermal oxidation on structure and photoelectronic properties of silicon oxide in monocrystalline silicon solar cells

This paper concerns the topic of surface passivation properties of rapid thermal oxidation on p-type monocrystalline silicon wafer for use in screen-printed silicon solar cells. It shows that inline thermal oxidation is a very promising alternative to the use of conventional batch type quartz tube furnaces for the surface passivation of industrial phosphorus-diffused emitters. Five minutes was the most favorable holding time for the rapid thermal oxidation growth of the solar cell sample, in which the average carrier lifetime was increased 19.4 μs. The Fourier transform infrared spectrum of the rapid thermal oxidation sample, whose structure was Al/Al-BSF/p-type Si/n-type SiP/SiO2/SiNx/Ag solar cell with an active area of 15.6 cm2, contained an absorption peak at 1085 cm−1, which was associated with the Si–O bonds in silicon oxide. The lowest average reflectance of this sample is 0.87%. Furthermore, for this sample, its average of internal quantum efficiency and conversion efficiency are respectively increased by 8% and 0.23%, compared with the sample without rapid thermal oxidation processing.

Indium sulfide thin films as window layer in chemically deposited solar cells

Indium sulfide (In2S3) thin films have been synthesized by chemical bath deposition technique onto glass substrates using In(NO3)3 as indium precursor and thioacetamide as sulfur source. X-ray diffraction studies have shown that the crystalline state of the as-prepared and the annealed films is β-In2S3. Optical band gap values between 2.27 and 2.41eV were obtained for these films. The In2S3 thin films are photosensitive with an electrical conductivity value in the range of 10−3–10−7(Ωcm)−1, depending on the film preparation conditions. We have demonstrated that the In2S3 thin films obtained in this work are suitable candidates to be used as window layer in thin film solar cells. These films were integrated in SnO2:F/In2S3/Sb2S3/PbS/C–Ag solar cell structures, which showed an open circuit voltage of 630mV and a short circuit current density of 0.6mA/cm2.

The degradation mechanism of TiPdAg solar cell contacts by an accelerated electrochemical testing technique

An accelerated experimental study on encapsulated solar cells with TiPdAg contacts has been made. The degradatio properties of TiPdAg solar cell metallization are described. It is shown that the encapsulation materials, which act as an electrolyte, play a major role in the deterioration reaction mechanisms. A qualitative comparison is made of the commonly used polyvinylbutyral (PVB) with an ethylene-vinyl acetate (EVA) encapsulant. Silver migration was detected in PVB but was not observed in EVA, indicating the advantages of EVA over PVB in reducing corrosion problems in modules. Electrical performance measurements (current-voltage curves) showed a reduction in the solar cell power output due to a loss in the encapsulation transparency (optical loss) caused by the presence of corrosion products on and around the metallization grid lines.