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Recently, III-V/c-Si heterojunction (c-Si HJ) tandem solar cells received considerable attention owing to their high conversion efficiency. In a tandem configuration, current matching has a significant impact on conversion efficiency. Specifically, in the two-terminal tandem structure, the sub-cell with the lowest current density (Jsc) dominates the Jsc of the tandem cell, which in turn, dominates the overall conversion efficiency of the tandem device. Meanwhile, in a four-terminal tandem structure, although the current matching condition is not mandatory, an efficient light distribution is necessary to achieve high efficiency in each sub-cell, which in turn results in a high efficiency of the tandem cell. Herein, we propose two- and four-terminal GaAs/c-Si HJ tandem solar cells using effective albedo reflections (RA) to overcome the aforementioned limitations. As RA increased, the current density of the c-Si HJ solar cells increased from 3.07 mA/cm2 (RA = 10%) to 39.90 mA/cm2 (RA = 100%) on the rear side of the cell, thereby, overcaming the existing current density limit. In addition, we investigated the tandem structures via simulation to provide a practical direction for achieving high efficiency. Finally, normalised outputs of 40.00% and 40.31% were achieved for the two-terminal and four-terminal GaAs/c-Si HJ bifacial tandem solar cells, respectively, with a real-life albedo from common ground surfaces, such as sand.

We report on the tunnel oxide passivated contact (TOPCon) using a crystalline nanostructured silicon-based layer via an experimental and numerical simulation study. The minority carrier lifetime and implied open-circuit voltage reveals an ameliorated passivation property, which gives the motivation to run a simulation. The passivating contact of an ultra-thin silicon oxide (1.2 nm) capped with a plasma enhanced chemical vapor deposition (PECVD) grown 30 nm thick nanocrystalline silicon oxide (nc-SiOx), provides outstanding passivation properties with low recombination current density (Jo) (~1.1 fA/cm2) at a 950 °C annealing temperature. The existence of a thin silicon oxide layer (SiO2) at the rear surface with superior quality (low pinhole density, Dph < 1 × 10−8 and low interface trap density, Dit ≈ 1 × 108 cm−2 eV−1), reduces the recombination of the carriers. The start of a small number of transports by pinholes improves the fill factor (FF) up to 83%, reduces the series resistance (Rs) up to 0.5 Ω cm2, and also improves the power conversion efficiency (PEC) by up to 27.4%. The TOPCon with a modified nc-SiOx exhibits a dominant open circuit voltage (Voc) of 761 mV with a supreme FF of 83%. Our simulation provides an excellent match with the experimental results and supports excellent passivation properties. Overall, our study proposed an ameliorated knowledge about tunnel oxide, doping in the nc-SiOx layer, and additionally about the surface recombination velocity (SRV) impact on TOPCon solar cells.

In this paper, some degradation and failure modes of PV modules are discussed. PV module reliability became a topic of extreme importance since manufacturers generally establish tight warranty periods with customers, despite having degradation rates around 0.6–0.7% a year. Special attention is given to corrosion, light-induced degradation (LID), and light and elevated induced degradation (LeTID) due to its frequency and contribution to the overall degradation rate. An overview of the corrosion mechanisms in metal contacts and their interaction with encapsulant and backsheet deterioration are presented. A systematic description of the types of corrosion by-products and their respective expected colors when observed through an optical microscope is presented. The most common techniques to evaluate corrosion are highlighted, as well as some observations and conclusions based on the results from previous studies. As for LID and LeTID, the main variants of concern to the photovoltaic industry are identified along with the mechanisms responsible for the generation of recombination active defects. At last, prevention and correction measures are described in order to minimize economic losses.

The main goal of solar cell technology is to attain high efficiency, long durability, mass-production, cost-effectiveness, and made with eco-friendly materials. Among the various crystalline silicon solar cell technologies, Tunneling Oxide Passivated Contact (TOPCon) solar cell has its unique style in terms of the structure and carrier transport manner, which predominately decreases the metal contact recombination and gives 1-D carrier transport. A very high efficiency of 26% for TOPCon solar cells has been achieved with the industrial screen print technology and obtained high cell parameter values of Voc and fill factor as 732.3 mV and 84.3% respectively. The tunnel oxide thickness (maintaining

Renewable energy has become more popular with the increase in the use of solar power. Consequently, the disposal of defective and old solar panels is gradually increasing giving rise to a new problem. Furthermore, the efficiency and power output decreases with aging. Researchers worldwide are engaged in solving this problem by developing eco-module technologies that restore and reuse the solar panels according to the defect types rather than simple disposal. The eco-module technology not only solves the environmental problem, but also has economic advantages, such as extending the module life. Replacement of encapsulants contributes to a major portion of the module maintenance plan, as the degradation of encapsulants accounts for 60% of the problems found in modules over the past years. However, the current International Electrotechnical Commission (IEC) standard testing was designed for the commercialization of solar modules. As the problem caused by long-term use is not considered, this method is not suitable for the quality assurance evaluation of the eco-module. Therefore, to design a new accelerated test, this paper provides an overview of EVA degradation and comparison with the IEC and accelerated tests.

The HF treatment removes the native oxide and lays behind the dangling bonds over the Si surface which causes the increment in density of interface traps (Dit) through the direct deposition of high-k dielectric on Si. Here, we propose the facile method for reduction of interface traps and improvement in barrier height with the (NH4)2S treatment on Al2O3/Si interfaces, which can be used as the base for the non-volatile memory device. The AFM was used to optimize the treatment time and surface properties, while XPS measurements were carried out to study the interface and extract the barrier height (ΦB). The short period of 20 s treatment shows the improvement in the barrier height (1.02 eV), while the one order reduction in the Dit (0.84 × 1012 cm2/eV) of sulfur passivated Al/Al2O3/Si MOS device. The results indicate the favorable passivation of the dangling bonds over the Si surfaces covered by sulfur atoms.

The characteristics of HfO2 thin films obtained with and without ultraviolet (UV) exposure post-treatment are discussed. First, 30-nm-thick HfO2 thin films are deposited on silicon wafer substrates using atomic layer deposition followed by a combination of UV exposure and low-temperature thermal post-treatment. Compared with the samples without UV treatment, the HfO2 samples with post-treatment showed a smaller suboxide bond proportion of 2.59%, along with increased crystallinity. The use of a UV-treated gate dielectric HfO2 film in a MOS capacitor device results in lower interface trap and fixed charge densities. Furthermore, the dielectric constant of the HfO2 thin film with the treatment is 22.03, which is higher than that of the film without the treatment, that is, 14.98. In addition, the device capacitance was improved by 56% with the treatment. These results demonstrate the significant potential of the proposed post-treatment process in improving the quality of HfO2 thin films for semiconductor devices.

Photovoltaic (PV) panels are generally treated as the most dependable components of PV systems; therefore, investigations are necessary to understand and emphasize the degradation of PV cells. In almost all specific deprivation models, humidity and temperature are the two major factors that are responsible for PV module degradation. However, even if the degradation mode of a PV module is determined, it is challenging to research them in practice. Long-term response experiments should thus be conducted to investigate the influences of the incidence, rates of change, and different degradation methods of PV modules on energy production; such models can help avoid lengthy experiments to investigate the degradation of PV panels under actual working conditions. From the review, it was found that the degradation rate of PV modules in climates where the annual average ambient temperature remained low was -1.05% to -1.16% per year, and the degree of deterioration of PV modules in climates with high average annual ambient temperatures was -1.35% to -1.46% per year; however, PV manufacturers currently claim degradation rates of up to -0.5% per year.

In this study, technology computer-aided design (TCAD) was used to investigate carrier selective contact solar cell performance based on the boundary of tunneling oxide and electron selective contact layer properties. The role of tunneling oxide quality in the passivation and inter-diffusion properties of the plasma-enhanced chemical vapor deposition of phosphorus-doped amorphous silicon as an electron selective contact layer is studied for carrier selective contact solar cells. Tunnel oxide quality varies according to the ratio of Si4+ to Si2+ state. For the Si4+/Si2+ ratio of 4, open-circuit voltage of 730 mV and the lowest interface trap density of 5.3 × 1010 cm−2 eV−1 are achieved. The change in diffusion depth of the doped layer with respect to the annealing temperature is analysed by transmission electron microscopy (TEM)/energy dispersive X-ray spectroscopy (EDS) measurement. Carrier selective contact solar cell parameters are optimized by incorporating the experimental values of interface trap density, inter-diffused impurity concentration, and depth in the Quokka 3 TCAD tool. Solar cell conversion efficiency of 24.31% was obtained. To understand the response of carrier selective solar cell to the environmental changes, the output characteristics of the solar cell were studied by varying the illumination temperature by 10% of the standard test conditions (STC) and temperature from 277 K to 377 K (difference of 100 K).

Shingled technology is the latest cell interconnection technology developed in the photovoltaic (PV) industry due to its reduced resistance loss, low-cost, and innovative electrically conductive adhesive (ECA). There are several advantages associated with shingled technology to develop cell to module (CTM) such as the module area enlargement, low processing temperature, and interconnection; these advantages further improves the energy yield capacity. This review paper provides valuable insight into CTM loss when cells are interconnected by shingled technology to form modules. The fill factor (FF) had improved, further reducing electrical power loss compared to the conventional module interconnection technology. The commercial PV module technology was mainly focused on different performance parameters; the module maximum power point (Pmpp), and module efficiency. The module was then subjected to anti-reflection (AR) coating and encapsulant material to absorb infrared (IR) and ultraviolet (UV) light, which can increase the overall efficiency of the shingled module by up to 24.4%. Module fabrication by shingled interconnection technology uses EGaIn paste; this enables further increases in output power under standard test conditions. Previous research has demonstrated that a total module output power of approximately 400 Wp may be achieved using shingled technology and CTM loss may be reduced to 0.03%, alongside the low cost of fabrication.

We report the influence of reactive oxygen (O2) and argon (Ar) plasma based ITO:Zr bi-layers for silicon heterojunction (SHJ) solar cells. The purpose of reactive O2 sputtered ITO:Zr was to improve the Hall mobility and work function while the Ar based ITO:Zr films play an important role to maintain good electrical characteristics. The thickness of reactive O2 based ITO:Zr films was fixed at 15 nm while Ar based films was varied from 65 to 125 nm, respectively. ITO:Zr bi-layers with the thickness of 15/105 nm deposited by O2 and Ar plasma, respectively, showed lowest resistivity of 2.358 × 10−4 Ω cm and high Hall mobility of 39.3 cm2/V · s. All ITO:Zr bi-layers showed an average transmittance of above 80% in the visible wavelength (380–800 nm) region. Work function of ITO:Zr bi-layers was calculated from the X-ray photoelectron spectroscopic (XPS) data. The ITO:Zr work function was enhanced from 5.3 eV to 5.16 eV with the variation of ITO:Zr bi-layers from 15/65 to 15/125 nm, respectively. Front barrier height in SHJ solar cells can be modified by using TCO films with high work function. The SHJ solar cells were fabricated by employing the ITO:Zr bi-layer as front anti-reflection coating. The SHJ solar cells fabricated on ITO:Zr bi-layer with the thickness of 15/105 nm showed the best photo-voltage parameters as; Voc = 739 mV, Jsc = 39.12 mA/cm2, FF = 75.97%, η = 21.96%.

Reducing crystalline silicon (c-Si) wafer thickness is an effective method to reduce the fabrication cost as it constitutes a major portion of the photovoltaic module cost. However, the open-circuit voltage and fill factor depend on the wafer thickness; further, the short-circuit current density (JSC), affects the device performance negatively. Therefore, light trapping is vital for increasing the JSC of Si solar cells. Consequently, it is essential for improving the conversion efficiency of the solar cell and reduce its production cost by decreasing the wafer thickness. It can be assumed that the thickness of the Si wafer will gradually achieve a minimum value of ~ 100 μm in the future. Therefore, reducing the as-cut wafer thickness will result in a more efficient use of Si. This paper reports the surface modification for light trapping based on the Si solar cell application. Additionally, we introduce methods for surface modification, such as front-side texturing and rear-side polishing.

We report the effect of variation of the channel width-to-length aspect ratio on the negative bias stress instability and the impact of the source/drain contact resistance on the electrical properties of amorphous-InGaZnO (IGZO) thin-film transistor (TFT) arrays. An asymmetric degradation of the threshold voltage (Vth) was observed over a wide range of negative stress bias in the IGZO TFT arrays. The lowest ∆Vth of 0.8 V and good stability with an increase in stress time were observed for the array having the channel aspect ratio of ~ 1.5, whereas the highest ∆Vth of 5.2 V was observed for the array having the channel aspect ratio of ~ 2.5. The drain-induced barrier lowering (DIBL) mechanism and the transmission line method (TLM) were used to investigate this abnormal degradation. The maximum DIBL of 50.2 mV/V was calculated for the array having a channel width/length of 4.4/11 μm. Application of the TLM revealed a channel resistance of 10.4 kΩ μm at a small gate bias of 0.5 V. Degradation of the electrical properties was observed for the array having an aspect ratio of 2.5 owing to poor ohmic contact with the channel. This investigation suggests that proper selection of the aspect ratio is important in the design of small-scale TFT arrays, as it can help to reduce the degradation of the electrical properties at a smaller dimension. Short-channel effects such as electron trapping and parasitic resistances can be minimized via improvement of the bias stress instability by use of a width-to-length aspect ratio of ~ 1.5. The findings in this report are beneficial for designing ultra-high-definition active-matrix displays.

Light-trapping phenomenon is limited due to non-uniform surface structure of transparent conducting oxide (TCO) films. The proper control of surface structure with uniform cauliflower TCO films may be appropriate for efficient light trapping. We report a light-trapping scheme of SF6/Ar plasma-based textured glass surfaces for high root-mean-square (RMS) roughness and haze ratio of ITO films. It was observed that the variation in Ar flow ratio in SF6/Ar plasma during the inductive coupled plasma-reactive ion etching (ICP-RIE) process was an important factor to improve the haze ratio of textured glass. The SF6/Ar plasma textured glass showed low etching rates due to the presence of various metal elements, such as Al, B, F, and Na. The ITO films were deposited on SF6/Ar plasma-textured glass substrates showed the high RMS roughness (433 nm) and haze ratio (67.8%) in the visible wavelength region. The change in surface structure has a negligible influence on the electrical properties of ITO films. The TCO films deposited on periodic textured glass surfaces with high RMS roughness and haze ratio are proposed for high-efficiency amorphous silicon (a-Si) thin-film solar cells.

This inclusive study provides detailed information regarding the evolution of rear emitter silicon heterojunction solar cells. Silicon heterojunction (SHJ) solar cells of a p-type on the rear side have garnered increasing attention for various reasons. First, owing to a limitation of the p-type hydrogenated amorphous silicon layer, further optimization relative to an n-type cannot be achieved, and an accumulation of electrons at the front side allows utilizing an n-type wafer to affirm a lateral current transport. Second, better thin n-type nanocrystalline silicon (oxide) contact layers compared to p-type wafers are grown, and allow greater freedom in the structural design. The optical properties of the front side’s transparent conductive oxide (TCO) layer can be emphasized owing to a lateral transport on the cells, and majority of the carriers are affirmed through a Si substrate. In the instance of a rear emitter, the TCO layer is in relief to an adjustment inhibiting the contact resistance between TCO/a-Si:H(p). The fabrication was done in such a manner of SHJ rear emitter solar cells that they achieve greater optimization and overall efficiency of 23.46%.

We report the effects of the nitride passivation layer on the structural, electrical, and interfacial properties of Ge metal-oxide-semiconductor (MOS) devices with a hafnium oxide (HfO₂) gate dielectric layer deposited on p-type 〈100〉 Ge substrates. X-ray photoelectron spectroscopy analysis confirmed the chemical states and formation of HfO₂/Ge₃N₄ on Ge. The interfacial quality and thickness of the layers grown on Ge were confirmed by high-resolution transmission electron microscopy. In addition, the effects of post-deposition annealing (PDA) on the HfO₂/Ge₃N₄/Ge and HfO₂/Ge samples at 400 °C in an (FG+O₂) ambient atmosphere for 30 min were studied. After PDA, the HfO₂/Ge₃N₄/Ge MOS device showed a higher dielectric constant (k) of ~21.48 and accumulation capacitance of 1.2 nF, smaller equivalent oxide thickness (EOT) of 1.2 nm, and lower interface trap density (Dit) of 4.9×1011 cm-2 eV-1 and oxide charges (Qeff) of 7.8×1012 cm-2 than the non-annealed sample. The I-V analysis showed that the gate leakage current density of the HfO₂/Ge₃N₄/Ge sample (0.3-1 nA cm-2 at Vg = 1 V) was half of that of the HfO₂/Ge sample. Moreover, the barrier heights of the samples were extracted from the Fowler-Nordheim plots. These results indicated that nitride passivation is crucial to improving the structural, interfacial, and electrical properties of Ge-based MOS devices.

In this study, we investigated the effect of plasma treatment on an indium tin oxide (ITO) film under an ambient Ar atmosphere. The sheet resistance of the plasma-treated ITO film at 250 W (37.6 Ω/sq) was higher than that of the as-deposited ITO film (34 Ω/sq). Plasma treatment was found to decrease the ITO grain size to 21.81 nm, in comparison with the as-deposited ITO (25.49 nm), which resulted in a decrease in the Hall mobility. The work function of the Ar-plasma-treated ITO (WFITO=4.17 eV) was lower than that of the as-deposited ITO film (WFITO = 5.13 eV). This lower work function was attributed to vacancies that formed in the indium and oxygen vacancies in the bonding structure. Rear-emitter silicon heterojunction (SHJ) solar cells fabricated using the plasma-treated ITO film exhibited an open circuit voltage (VOC) of 734 mV, compared to SHJ cells fabricated using the as-deposited ITO film, which showed a VOC of 704 mV. The increase in VOC could be explained by the decrease in the work function, which is related to the reduction in the barrier height between the ITO and a-Si:H (n) of the rear-emitter SHJ solar cells. Furthermore, the performance of the plasma-treated ITO film was verified, with the front surface field layers, using an AFORS-HET simulation. The current density (JSC) and VOC increased to 39.44 mA/cm2 and 736.8 mV, respectively, while maintaining a WFITO of 3.8 eV. Meanwhile, the efficiency was 22.9% at VOC = 721.5 mV and JSC = 38.55 mA/cm2 for WFITO = 4.4 eV. However, an overall enhancement of 23.75% in the cell efficiency was achieved owing to the low work function value of the ITO film. Ar plasma treatment can be used in transparent conducting oxide applications to improve cell efficiency by controlling the barrier height.

Nowadays, the search for novel compounds by chemical synthesis is in trend. Herein, we report the deposition of Cd1-x-yZnxCuySe (0.025 ≤ x = y ≤ 0.15) films by facile, industry-oriented chemical synthesis. The Cd1-x-yZnxCuySe thin films were deposited at the optimized growth conditions (temperature = 70 ± 0.1 °C, pH = 10.3 ± 0.1, substrate rotation speed = 70 ± 2 rpm and time = 100 min). As-synthesized thin films were characterized for physical, chemical, topographical and electrical attributes. The study of vibrational modes in Cd1-x-yZnxCuySe thin films was done with the help of Raman spectroscopy. Improvement in surface topography with the integration of Cu2+ and Zn2+ into the CdSe lattice has been noticed by the atomic force microscopy (AFM). The electrochemical impedance spectroscopy revealed lower values of Rs and Rct for x = y = 0.05 composition. Chemical deposition of Cd1-x-yZnxCuySe thin films may offer an excellent way to fabricate quaternary chalcogenide-based absorber materials for solar cells.

Excellent surface passivation with a localised back surface field (LBSF) formation is the key parameter for increasing the efficiency of PERC cells. In this regard, the additional use of rear multi-stack passivation layers (Al2O3/SiNX) and local laser opening of the LBSF increase the production cost. In addition, these stacked layers and the laser process require additional tools, which creates a compatibility barrier for studies conducted in small-scale industrial laboratories. Rear multi-stack passivation layers (Al2O3/SiNX) and a front SiNX anti-reflection coating (ARC) layer were changed using a one-step thermal oxidation process. The emitter doping and thermal SiO2 oxidation layer were optimised for the front ARC and rear passivation layer. The formation mechanism of the LBSF was investigated by varying the firing conditions and the Al dot size. Scanning electron microscopy images confirmed the thickness of the LBSF. The fabricated cell exhibited an efficiency of 20.05% with a fill factor (FF) of 78%, a current density (JSC) of 39.3 mA/cm2, and an open-circuit voltage (VOC) of 655 mV under a spectral condition of AM 1.5G. A significant improvement in the recombination current density (J0) (314 fA/cm2) was achieved as compared with the fire-through full BSF solar-cell process (933 fA/cm2).

Effects of post deposition annealing (PDA) atmosphere, including oxygen (O2) gas and forming gas (FG), on interfacial and electrical properties of a HfO2 gate dielectric on nitrided Ge are analyzed. Experiments to study the dielectric morphology, interface quality, and chemical composition of HfO2/Ge3N4/Ge devices were carried out using X-ray diffraction, high-resolution transmission electron microscopy (HRTEM) imaging, and X-ray photoelectron spectroscopy (XPS) measurements, respectively. The XPS study confirmed that O2 PDA effectively improves the HfO2 film stoichiometry, and the stability of the interface between HfO2/Ge3N4/Ge stacks is enhanced. Further, HRTEM images showed that the interface between HfO2/Ge3N4/Ge stacks for O2-annealed devices was smooth, uniform, and flat. The experimental results for devices annealed in O2 at 500 °C exhibited improved interfacial and electrical characteristics, such as a high dielectric constant of ~19.50; high capacitance, 1.24 nF, low equivalent oxide thickness, 1.74 nm; interface trap density, 2.18 × 1011 cm−2 eV−1; oxide charges, 2.50 × 1012 cm−2; and gate leakage currents in the order nA of 0.5 × 10−9 A/cm2, as compared with FG annealing devices. The Fowler−Nordheim tunneling current conduction mechanism was also verified. Therefore, these results are evidence that the O2 PDA process improves the interfacial and electrical properties of HfO2/Ge3N4/Ge metal-oxide-semiconductor (MOS) devices as compared with FG annealing, which is important for future Ge-based complementary MOS device performance and reliability.

Effective carrier contact with excellent surface passivation is essential for archiving high efficiency silicon solar cells. In this study, optical, passivation and stoichiometric characteristics of MoOx thin films were analyzed by varying thickness, temperature and ambient annealing. The 10 nm thick MoOx films showed high optical transmittance (89.81%) in the visible near infra-red (NIR) wavelength (380–1100) nm region and wide optical bandgap of 3.25 eV. An improved minority carrier lifetime of 2.24 ms was recorded for O2 ambient at 130 °C due to less additional defects in the MoOx films. X-rays photoelectron spectroscopic analysis confirmed that O2 ambient annealing greatly influenced the MoOx stoichiometric and reduce the formation defective state densities at the Fermi energy initiating from the tail of an oxygen vacancy and inducted the defect band within the energy bandgap. Carrier selective contact (CSC) solar cells were fabricated by using 10 nm thick MoOx film as hole extraction layer exhibited the high performance as; open circuit voltage (Voc) = 708 mV, current density (Jsc) = 37.80 mA/cm2, fill factor (FF) = 74.95% and efficiency (η) = 20.06%. These results implies that the MoOx is an important material to use in future CSC solar cell applications with the concept of new advantages such as dopant free, non-toxic and low temperature fabrication process.

Transition metal oxides (TMO) are extensively applied as a surface passivation and carrier-selective contact layer through replacing boron/phosphorus doped emitter layers in silicon heterojunction (SHJ) solar cell applications. In this regard, molybdenum oxide (MoO3) has drawn a significant attention as a hole extraction layer owing properties such as wide bandgap (∼3 eV), high work function (>6 eV) and low temperature deposition. Thus, we fabricated SHJ solar cells with a dopant-free MoOx applied at the front surface contact layer. Thermally evaporated MoOx films were exhibited optical characteristics such as high transmittance, high bandgap and low absorption coefficient as compared to a-Si:H(p) and μc-SiOx:H (p) layers. X-ray photoelectron spectroscopy (XPS) analysis confirmed the stoichiometric and oxidation deficiency states of the of the MoOx layers. Whereas, MoOx films undergoing long-term air exposure showed an increase in Mo5+ cations due to the increased oxygen vacancy. The fabricated MoOx/c-Si heterojunction solar cells achieved a significant power conversion efficiency (η) of 20%, best open circuit voltage (Voc) of 695 mV, high short circuit current density (Jsc) of 38.88 mA/cm2 and a fill factor (FF) of 74.0%. These results implying that MoOx is as an excellent dopant-free material for alternate p-doped a-Si:H emitter layers in SHJ solar cell applications.

In silicon heterojunction (SHJ) solar cells, a wide bandgap material with a high work function is widely used as the hole extraction pathway to attain high efficiency. We introduced a molybdenum oxide (MoOx) film as an effective hole-transfer layer in carrier selective contact (CSC) solar cells by virtue of its wide bandgap along with high work function. The passivation characteristics, optical and electrical properties of MoOx films were investigated by differing thickness and work function. The combination of 6 nm hydrogenated intrinsic amorphous silicon (a-Si:H(i)) and 7 nm thermally evaporated MoOx passivation layers provides excellent passivation properties, reduces carrier recombination, and improves the cell performance. The synthesized CSC solar cells showed promising results, with an open-circuit voltage (Voc) of 708 mV, short-circuit current (Jsc) = 37.38 mA cm−2, fill factor (FF) = 74.59%, and efficiency (η) = 19.75%. To justify the obtained result, an AFORS HET simulation was conducted based on the experimental results. The high work function and wide bandgap MoOx/c-Si(n) interface developed a considerable built-in potential and suppressed the electron–hole pair recombination mechanism. The CSC solar cell’s simulated performance was enhanced from 1.62 to 23.32% by varying the MoOx work function (ΦMoOx) from 4.5 to 5.7 eV.

Recently, selective emitter (SE) technology has attracted renewed attention in the Si solar cell industry to achieve an improved conversion efficiency of passivated-emitter rear-contact (PERC) cells. In this study, we presented a novel technique for the SE formation by controlling the surface morphology of Si wafers. SEs were formed simultaneously, that is, in a single step for the doping process on different surface morphologies, nano/micro-surfaces, which were formed during the texturing processes; in the same doping process, the nano- and micro-structured areas showed different sheet resistances. In addition, the difference in sheet resistance between the heavily doped and shallow emitters could be controlled from almost 0 to 60 Ω/sq by changing the doping process conditions, pre-deposition and driving time, and temperature. Regarding cell fabrication, wafers simultaneously doped in the same tube were used. The sheet resistance of the homogeneously doped-on standard micro-pyramid surface was approximately 82 Ω/sq, and those of the selectively formed nano/micro-surfaces doped on were on 62 and 82 Ω/sq, respectively. As a result, regarding doped-on selectively formed nano/micro-surfaces, SE cells showed a JSC increase (0.44 mA/cm2) and a fill factor (FF) increase (0.6%) with respect to the homogeneously doped cells on the micro-pyramid surface, resulting in about 0.27% enhanced conversion efficiency.

This paper confirms that the electrical characteristics of FinFETs such as the on/off ratio, drain-induced barrier lowering (DIBL), and sub-threshold slope (SS) can be improved by optimizing the FinFET spacer structure. An operating voltage that can maintain a life of 10 years or more when hot-carrier injection is extracted. An excellent on/off ratio (7.73&times, 107) and the best SS value were found at 64.29 mV/dec with a spacer length of 90 nm. Under hot carrier-injection conditions, the supply voltages that meet the 10-year lifetime condition are 1.11 V, 1.18 V, and 1.32 V for spacer lengths of 40 nm, 80 nm, and 120 nm, respectively. This experiment confirmed that, even at low drain voltages, the shorter is the spacer length, the greater is the deterioration. However, this increasing maximum operating voltage is very small when compared to the increase in the driving voltage required to achieve similar performance when the spacer length is increased, therefore, the effective life is expected to decrease. The results indicate that structural optimization must be performed to increase the driving current of the FinFET and prevent degradation of the analog performance.

In this work, to ameliorate the quantum efficiency (QE), we made a valuable development by using wide band gap material, such as lithium fluoride (LiFx), as an emitter that also helped us to achieve outstanding efficiency with silicon heterojunction (SHJ) solar cells. Lithium fluoride holds a capacity to achieve significant power conversion efficiency because of its dramatic improvement in electron extraction and injection, which was investigated using the AFORS-HET simulation. We used AFORS-HET to assess the restriction of numerous parameters which also provided an appropriate way to determine the role of diverse parameters in silicon solar cells. We manifested and preferred lithium fluoride as an interfacial layer to diminish the series resistance as well as shunt leakage and it was also beneficial for the optical properties of a cell. Due to the wide band gap and better surface passivation, the LiFx encouraged us to utilize it as the interfacial as well as the emitter layer. In addition, we used the built-in electric and band offset to explore the consequence of work function in the LiFx as a carrier selective contact layer. We were able to achieve a maximum power conversion efficiency (PEC) of 23.74%, fill factor (FF) of 82.12%, Jsc of 38.73 mA cm−2, and Voc of 741 mV by optimizing the work function and thickness of LiFx layer.