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This study investigated the integration of perovskite solar cells (PSCs) on stainless steel (SS) substrates for application in building-integrated photovoltaics (BIPV). Using advanced atomic force microscopy measurements, we confirmed that enhanced substrate roughness increased the reflectance along an interface. Consequently, a remarkable final efficiency of 11.9% was achieved. Notably, PSCs, known for their exceptional efficiency of 26.1%, can overcome the inherent efficiency limitations of SS-based thin-film solar cells. In this study, a PSC with an efficiency of 14% was fabricated on a flexible SS substrate. This study is a significant step towards advancing sustainable energy solutions for BIPV applications. The global shift towards renewable energy sources has catalyzed intensive research and development efforts, rendering the exploration of alternative materials and manufacturing processes a priority. The success of PSCs on SS substrates underscores their promise to achieve a balance between efficiency and versatility in BIPV solutions. Moreover, our findings reveal that controlling the substrate surface characteristics can significantly enhance the performance of PSCs, offering a pathway toward greater energy efficiency and sustainability in the construction industry. [ABSTRACT FROM AUTHOR]

This review discusses the use of evaporation, chemical vapor deposition, and sputtering as the three main dry deposition techniques currently available for fabricating perovskite solar cells. We outline the distinct advantages that each method offers in terms of film quality, control, and scalability. Additionally, recent advancements in process optimization and the integration of dry deposition with other fabrication techniques are highlighted. Thus, this review provides valuable insights into the potential of dry deposition processes to produce high-performance perovskite solar cells and aids researchers and industry professionals in selecting the most suitable technique for the fabrication of efficient and stable devices. [ABSTRACT FROM AUTHOR]

Conformal deposition of perovskite films on textured silicon surfaces using a dry process is crucial for producing high‐performance perovskite/silicon tandem solar cells. Herein, a radio frequency magnetron sputtering process is used with a PbI2 target to deposit precursor films. Iodination, thermal annealing, and dimethyl sulfoxide treatment are employed as posttreatment processes to improve the stoichiometry, crystallinity, and surface morphology of the PbI2 precursor. The precursor films are converted into perovskite using direct contact conversion process, and the interfacial and bulk properties are enhanced by methylamine vapor annealing to fabricate perovskite solar cells with a power conversion efficiency of 12.2%. Also, 18.3% efficiency is confirmed at a wider voltage sweep range, which suggests that further efficiency improvement is possible by removing defects inside the perovskite. Finally, uniform perovskite films are conformally deposited on a 25 cm2 textured silicon surface. With such high‐efficiency potential and conformality, the method of sputtering PbI2 can open a new way to fabricate perovskite/silicon tandem solar cells. [ABSTRACT FROM AUTHOR]

Solar energy has gained prominence because of the increasing global attention received by renewable energies. This shift can be attributed to advancements and innovations in solar cell technology, which include developments of various photovoltaic materials, such as thin film and tandem solar cells, in addition to silicon-based solar cells. The latter is the most widely commercialized type of solar cell because of its exceptional durability, long-term stability, and high photoconversion efficiency; consequently, the demand for Si solar cells has been consistently increasing. PV modules are designed for an operation lifespan of 25–30 years, which has led to a gradual increase in the number of end-of-life PV modules. The appropriate management of both end-of-life and prematurely failed PV modules is critical for the recovery and separation of valuable and hazardous materials. Effective methods for end-of-life PV waste management are necessary to minimize their environmental impact and facilitate transition to a more sustainable and circular economy. This paper offers a comprehensive overview of the separation processes for silicon PV modules and summarizes the attempts to design easily recyclable modules for sustainable solar module development. Based on the studies summarized in this paper, suggestions are provided for future research. [ABSTRACT FROM AUTHOR]

The recent efficiency boosting of Cu(In,Ga)Se2 (CIGS) solar cells is undoubtedly triggered by heavy alkali postdeposition treatments (PDTs). However, the effects are not obvious under monolithically integrated CIGS modules where various current‐shunting sources can deteriorate the device performance. Herein, It is reported that KF PDT can effectively suppress the major shunting sources caused by P1 and P3 laser scribing for monolithic interconnection, reducing the cell‐to‐module (CTM) efficiency gap in CIGS photovoltaics. CIGS with NaF PDT exhibits nearly isotropic and high hole mobilities, causing a large CTM efficiency loss. CIGS with additional KF PDT, on the other hand, reveals much lower in‐plane hole mobility than the out‐of‐plane component, significantly increasing the P1 shunt resistance without exacerbating the photocarrier extraction in the active area. It is suggested that such anisotropic charge transport is due to carrier scattering by low‐conductivity phases at the CIGS grain boundaries. Furthermore, passivation of the front junction by KF PDT raises the tolerance to P3 scribing‐induced damage, increasing the P3 shunt resistance while preserving the junction property unlike the NaF PDT case. The work implies that the recent trend of employing heavy alkali PDTs for a high‐efficiency cell is also crucial for designing a high‐efficiency CIGS module. [ABSTRACT FROM AUTHOR]

This study focuses on boron‐doped p+polysilicon (poly‐Si) passivating contacts using spin‐on doping (SOD). Experimental conditions, including annealing conditions, SOD concentration, and poly‐Si thickness, were controlled to improve passivation. Based on the analysis results, the passivation quality mainly changes with indiffusion and doping concentration, causing Auger recombination and field effects. Meanwhile, grain size also influences the passivation quality but showed marginal characteristics. Through further optimization using an etch back and diffusion barrier, the efficiency of the flat reference solar cell was improved to 17.5% with an open‐circuit voltage of 695 mV using a p+ poly‐Si contact emitter, the highest reported efficiency using SOD on saw‐damage‐etched surfaces. This study includes a detailed analysis of SOD p+ poly‐Si and shows promising results with potential for application in tandem devices. Furthermore, the cell efficiency is expected to increase by controlling the doping profile and application of textured surfaces, selective emitters, and forming gas annealing (FGA). Highlights: The passivation quality of p + poly‐Si passivating contacts with boron SOD was investigated.The factors influencing the passivation quality of p+ poly‐Si were crystallinity (grain size), indiffusion of boron into the bulk, and doping concentration (field effect).The doping process was further optimized by controlling the boron indiffusion from the SOD source to c‐Si bulk using an additional diffusion barrier layer that controls the boron doping profile.Poly‐Si contact cells with both‐side flat surfaces and poly‐Si contacts showed a maximum efficiency of 17.5% with VOC of 695 mV when a developed p+ poly‐Si was applied at the front. This is the highest reported efficiency using boron SOD‐doped p+ poly‐Si emitter on saw‐damage‐etched flat surfaces.Based on a wide range of analyses and experimental results, a 3D energy band diagram of p+ poly‐Si/SiO x/c‐Si passivating contacts is exhibited.The cell result validates its potential for use in silicon‐based tandem solar cells and the efficiency can be further improved by applying textured surfaces, FGA, and selective emitter for improved metal contacts. [ABSTRACT FROM AUTHOR]

Conformal deposition of wide-bandgap perovskite films along pyramidal silicon surfaces through the dry process is essential for fabricating large-area textured silicon/perovskite tandem solar cells. However, it is difficult to control the composition of mixed perovskite films through dry processes because the deposition rate in organic and inorganic components is different when depositing perovskite films using a multi-source or premixed-source. In this study, MAPbI3 perovskite films were deposited through radio-frequency magnetron sputtering and dry conversion processes, and wide-bandgap perovskite films with mixed halide compositions were prepared by immersion in a MABr/IPA solution. Based on the results, the bandgap of the perovskite films increased with the immersion time. In addition, a uniform depth profile of the perovskite composition was observed in the film. Perovskite solar cells were manufactured to verify their electrical characteristics. Finally, wide-bandgap perovskite films were conformally deposited on textured silicon surfaces. These results show the great potential of applications in silicon/perovskite tandem solar cells. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) have emerged as the next generation of solar cells because of the promising nature of creating tandem solar cells with Si photovoltaics. Wide‐bandgap PSCs are developed to improve the power conversion efficiency (PCE) and stability of tandem devices. For the mass production of tandem solar cells, not only is a limitation of scalable coating a critical factor, but uncontrollable grain growth in ambient air impedes commercialization. Serious differences in morphology depending on the experimental environment are found. In the ambient air processing system, severe wrinkles and voids resulting in deteriorated photovoltaic performance are found as compared with those in N2 condition. It is suggested that humidity in the air plays a crucial role in the remaining perovskite intermediate phase and the rate of solvent evaporation during the spin‐coating procedure. Herein, void‐ and wrinkle‐free perovskite films using methyl ammonium chloride and formamide are fabricated, thus leading to efficient PSCs with a PCE of 20.6%. Furthermore, newly designed perovskite films to blade coating for large‐area fabrication as well as to semitransparent PSCs for a four‐terminal silicon/perovskite tandem solar cell with a PCE of 25.2% are applied. [ABSTRACT FROM AUTHOR]

Tandem solar cells which are electrically connected with various photoactive materials have the potential to solve the current challenges by exceeding the theoretically limited efficiency of single junction solar cells. Here the first monolithic organic/silicon tandem cell is reported based on a semitransparent polymer on a crystalline silicon (c‐Si) substrate. Herein, experimental results are presented for four‐terminal (4‐T) and monolithic two‐terminal (2‐T) organic/c‐Si tandem cells using organic cells with an inverted n‐i‐p structure and c‐Si cells with an n‐type TOPCon structure with detailed analysis. The best 4‐T tandem cell efficiency is 15.22%, and 2‐T results show that the top (organic) and bottom (c‐Si) cells are electrically connected by an open‐circuit voltage over 1.4 V. Further, a simulated efficiency of over 20% using the organic/c‐Si tandem is achieved, implying the tandem efficiency can be enhanced through further improvement of electric and optical characteristics with the optimization. [ABSTRACT FROM AUTHOR]

Carbon nanotube electrode–laminated perovskite solar cells in combination with n‐type tunnel oxide–passivated contact silicon solar cells demonstrate a high power conversion efficiency (PCE) of 24.42% when stacked in tandem. This is compared with conventional indium tin oxide/MoOx‐deposited perovskite solar cells which give an efficiency of 22.35% when stacked in the same four‐terminal tandem system. Despite higher transmittance of the carbon nanotube electrode than that of the indium tin oxide/MoOx in the infrared range, the carbon nanotube electrode‐laminated devices show lower transmittance in the same region due to the total internal reflection and scattering as evidenced by optical simulation. Yet, the exceptionally high PCE of the carbon nanotube electrode‐laminated semitransparent devices far exceeding than that of the indium tin oxide/MoOx‐deposited semitransparent top cell outweighs the effect of the optical transparency. Four types of silicon solar cells are compared as the bottom subcells, and the n‐type tunnel oxide‐passivated contact silicon solar cells are the best choice mainly due to their high absorption in the long‐wavelength region. The obtained 24.42% efficiency is one of the high PCEs among the reported four‐terminal perovskite–silicon solar cells, and this article is the first demonstration of the carbon nanotube electrode application in tandem solar cells. [ABSTRACT FROM AUTHOR]

This study proposes a hybrid solar cell structure for a highly efficient silicon solar cell obtained by combining two passivating contact structures, namely, a heterojunction and polysilicon passivating contact. Given that the major cause of the loss in efficiency of crystalline silicon solar cells is carrier recombination at the metal‐semiconductor junction, a passivating contact having high‐quality passivation and a low contact resistance was introduced. In this study, two major passivating contact solar cells were combined. By applying an intrinsic thin amorphous silicon layer at the front and a tunneling oxide at the rear, a hybrid silicon solar cell with an efficiency of 21.8% was fabricated. Moreover, to evaluate the potential efficiency limit and to suggest methods for improving the cell performance of the proposed amorphous silicon emitter tunnel oxide back contact structure, the cell efficiency was simulated, and the result indicated that an efficiency of 26% could be achieved by controlling the thickness and resistivity of the wafer. [ABSTRACT FROM AUTHOR]

Abstract In recent days few-layered or ultrathin molybdenum disulfide (MoS 2) one of the transition metal dichalcogenides (TMDs) is gaining serious attention for photovoltaics. TMD materials are able to absorb up to 5–10% of incident sunlight in less than 1 nm thickness to achieve an order of magnitude higher solar light absorption. Metal organic chemical vapor deposition (MOCVD) was employed to obtain atomic layered MoS 2 on SiO 2 /Si substrate which subsequently transferred on InP substrate using a simple transfer protocol. We realized photovoltaic operation in atomically few-layered MoS 2 by forming a type II heterojunction with low dopped p-InP, instead of widely used p-Si. The built-in electric field arised due to interface between n-MoS 2 and p-InP heterojunction is beneficial for the photogenerated carrier generation and separation. The solar cell device could achieve a power conversion efficiency of 0.11% with 1.87 mA/cm2 current density, first attempt of TMD based solar cell on InP substrate, demonstrating a promising solar cell performance. The obtained results pave the way for the integration of TMD materials with the InP substrate to obtain efficient solar cells. Highlights • n-MoS 2 /p-InP Heterojunction solar cell. • Atomic layered MoS 2 nanosheets. • MOCVD synthesis of MoS 2 nanosheets. • Use of p-InP substrate than conventional p-Si. • Power conversion efficiency of 0.11%. [ABSTRACT FROM AUTHOR]

Recently, Cu(InXGa(1−X))Se2 (CIGS) absorber layers have been extensively studied by many research groups for thin-film solar cell technology. CIGS material is particularly promising due to its exceptionally high absorption coefficient and large band gap range, which is adjustable as a function of alloy stoichiometry. To enhance the conversion performance of CIGS solar cells, understanding the CIGS structure and composition is a crucial challenge. We conducted a quantitative study to determine the bulk composition of the major elements such as Cu, In, Ga, and Se of four different CIGS photovoltaic cells. The compositional information was obtained by X-ray fluorescence (XRF), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and femtosecond laser ablation inductively coupled plasma mass spectrometry (fs-LA-ICP-MS). Then, the XRF concentration ratio was compared with the intensity ratio of fs-LA-ICP-MS to investigate the potential of accurate and rapid analysis using the fs-LA-ICP-MS technique. In contrast to the bulk information, the surface techniques can supply detailed information about the chemical composition across the depth profile. Here, elemental depth distributions of CIGS thin films were investigated using magnetic sector secondary ion mass spectrometry (SIMS) and Auger electron spectroscopy (AES). The atomic distributions of four different CIGS absorber layers exhibited a good agreement although they were obtained using two different surface instruments, AES and SIMS. Comparative analysis results of different CIGS absorber layers using SIMS, AES, and fs-LA-ICP-MS provide us with the appropriate technique for the information of accurate composition in a rapid analysis time. Thanks to a simple approach using the Ga/(In + Ga) ratio, the optical band gap energy of the Cu(InXGa(1−X))Se2 quaternary layer was monitored in the entire CIGS layer. The elemental distribution and the band gap determination were then used to elucidate their relationship to the corresponding CIGS cell efficiency result. [ABSTRACT FROM AUTHOR]

Gapless interdigitated back contact (IBC) solar cells were fabricated with phosphorous back surface field on a boron emitter, using an ion implantation process. Boron emitter (boron ion implantation) is counter doped by the phosphorus back surface field (BSF) (phosphorus ion implantation) without gap. The gapless process step between the emitter and BSF was compared to existing IBC solar cell with gaps between emitters and BSFs obtained using diffusion processes. We optimized the doping process in the phosphorous BSF and boron emitter region, and the implied Voc and contact resistance relationship of the phosphorous and boron implantation dose in the counter doped region was analyzed. We confirmed the shunt resistance of the gapless IBC solar cells and the possibility of shunt behavior in gapless IBC solar cells. The highly doped counter doped BSF led to a controlled junction breakdown at high reverse bias voltages of around 7.5 V. After the doping region was optimized with the counter doped BSF and emitter, a large-area (5 inch pseudo square) gapless IBC solar cell with a power conversion efficiency of 22.9% was made. [ABSTRACT FROM AUTHOR]

Achieving high-specific-power and radiation hardness of solar cells is of great importance to perform tasks and achieve duration in space. Therefore, we investigated the proton irradiation resistance of ultralightweight CdS/CdTe thin film solar cells having high specific power values. High-energy proton beams (15 MeV) with doses ranging from 1×1012 to 1×1015 cm−2 were used, equivalent to more than 2000 years in low Earth orbit. Although 70 % decrease in cell conversion efficiency was observed after proton irradiation with dose of 1×1015 cm−2, it still maintained the photovoltaic performance. The specific power of the fabricated cell decreased from 358 W kg−1 to 109 W kg−1 after proton irradiation (dose=1×1015 cm−2), which is still comparable to specific powers of other types of solar cells. Our work indicated that reduction of short circuit current is a major factor of deterioration of the cell performance under the high energy proton irradiation. This work revealed that our lightweight CdS/CdTe solar cells have significant potential for the use in space applications: reduction of launch cost by achieving high specific power and assurance of durability over prolonged space missions. [ABSTRACT FROM AUTHOR]

This study evaluated the impact of partial shading on CuInxGa(1-x)Se2 (CIGS) photovoltaic (PV) modules equipped with bypass diodes. When the CIGS PV modules were partially shaded, they were subjected to partial reverse bias, leading to the formation of hotspots and a possible occurrence of junction damage. In a module with a cadmium sulfide buffer layer, hotspots and wormlike defects were formed. The hotspots were formed as soon as the modules were shaded; the hotspots caused permanent damage (wormlike defects) in the CIGS module. Specifically, the wormlike defects were caused by the window layer, leading to increased recombination and decay of the solar cell properties. However, a CIGS module with a zinc sulfide buffer layer did not exhibit the formation of hotspots or any visual damage. The reverse bias breakdown voltage of the CIGS PV module with the cadmium sulfide buffer layer was higher than that of the CIGS PV module with the zinc sulfide buffer layer. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Al2O3 layers fabricated with atomic layer deposition (ALD) show high levels of surface passivation on p- and n-type silicon wafers. In order to form front and rear electrodes, Al2O3 layers should undergo a firing process at a high peak temperature. Therefore, the Al2O3 layer must be stable under these conditions to maintain a high level of surface passivation during the firing process. In this study, Al2O3 layers fabricated with ALD were pre-annealed to enhance their thermal stability during the firing process. From quasi-steady state photoconductance (QSSPC) measurements, the difference between the implied Voc values of the pre-annealed and fired samples was found to be smallest (3 mV) when the sample was pre-annealed at 620 °C. The surface recombination rate calculated from capacitance-voltage ( C- V) measurements of metal-Al2O3-Si (metal-insulator-semiconductor) structures was shown to be low when the sample was pre-annealed at 600-650 °C. Thus, firing stability was achieved with pre-annealing at 620 °C by reducing the surface recombination rate. We conclude that it is necessary to pre-anneal the Al2O3 passivation layer at this specific temperature to reduce the degradation of the passivation quality of Al2O3 after the firing process. [ABSTRACT FROM AUTHOR]

We investigated the migration of Sn and Pb onto the Ag fingers of crystalline Si solar cells in photovoltaic modules aged in field for 6 years. Layers of Sn and Pb were found on the Ag fingers down to the edge of the solar cells. This phenomenon is not observed in a standard acceleration test condition for PV modules. In contrast to the acceleration test conditions, field aging subjects the PV modules to solar irradiation and moisture condensation at the interface between the solar cells and the encapsulant. The solder ribbon releases Sn and Pb via repeated galvanic corrosion and the Sn and Pb precipitate on Ag fingers due to the light-induced plating under solar irradiation. [ABSTRACT FROM AUTHOR]

Sol-gel derived nano-sized glass frits were incorporated into the Ag conductive ink for silicon solar cell metallization. This mixture was specifically formulated for inkjet printing on textured Si wafers with 80 nm thick SiN x anti reflection coating layers. The correlation between the contact resistance and interface microstructures were studied using scanning electron microscopy and transmission electron microscopy. In addition, the specific contact resistance between the front contact and emitter was measured at various firing conditions using the transfer length model. On an emitter with the sheet resistance of 60 Ω/sq, a specific contact resistance below 5 mΩ cm2 could be achieved at a peak firing temperature around 800 °C. We found that the incorporated nano-glass frit act as a very effective fire through agent, and an abundant amount of Ag crystallites was observed along the interface glass layer. (© 2015 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

This article investigates the impact of laser damage on the performance of a selective emitter solar cell fabricated using a laser doping process (LD). After the optimization of the laser doping process, an amorphous silicon layer with a thickness of approximately 100 Å was observed on the laser-doped emitter. The amorphous laser damage decreased the power conversion efficiency due to poor contact between the Ag front electrode and the selective emitter. To effectively improve the quality of the front contacts, a solution etch-back process was applied after the laser doping step (LEB), and the series resistance of the selective emitter solar cell was restored to 0.55 Ω cm 2 from around 1.0 Ω cm 2 . The contact formation during the LEB process clearly improved, and it was verified by comparing the densities of the Ag crystallites after Ag electrode removal from the LEB cell and the LD cell. The improvement in the formation of the front contact resulted in the LEB selective emitter solar cell recording a maximum 19.16% of power conversion efficiency, with a standard deviation of 0.055. [ABSTRACT FROM AUTHOR]

We developed a novel cost effective process scheme for the fabrication of highly efficient selective emitter solar cells, which uses a laser doping method combined with an etch back process. The laser doping process using a 150 ns pulse width green (532 nm) laser effectively controls the doping profiles to form a selective emitter. However, laser damage was created on the laser-doped surface and eventually the performances and stabilities of laser-doped cells were degraded due to this damage. Using a transmission electron microscope (TEM), the damage was examined and found to have a thickness of 40 nm of amorphous silicon. This thin damage layer was effectively removed in an acid mixture solution. The combined process of laser doping and etch back is called the laser etch back process. After removal of this thin damage layer, the cell efficiencies were significantly improved up to 19.17%. [ABSTRACT FROM AUTHOR]

ABSTRACT Back contacts for Si solar cells made by Al evaporation and screen printing Al paste were studied by transmission electron microscopy. Si was found to diffuse into the Al during heating. Si diffusion formed vacancies in the Si wafer and Al could then penetrate the Si wafer in spiked formations. The Al spikes retracted during cooling, leaving a doped back surface field region. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this work, nickel silicide was applied to tandem solar cells as an interlayer. By the process of thermal evaporation, a layer of NiOx, hole transport layer (HTL) was deposited on n+ poly-Si layer directly. Nickel silicide was simultaneously formed by nickel diffusion from NiOx to n+ poly-Si layer during the deposition and annealing process. The I–V characteristics of NiOx/n+ poly-Si contact with nickel silicide showed ohmic contact and low contact resistivity. This structure is expected to be more advantageous for electrical connection between perovskite top cell and TOPCon bottom cell compared to the NiOx/TCO/n+ poly-Si structure showing Schottky contact. Furthermore, nickel silicide and Ni-deficient NiOx thin film formed by diffusion of nickel can improve the fill factor of the two sub cells. These results imply the potential of a NiOx/nickel silicide/n+ poly-Si structure as a perovskite/silicon tandem solar cell interlayer. [ABSTRACT FROM AUTHOR]

An interdigitated back contact silicon solar cell with conversion efficiency of 19.6% was fabricated by screen-printing the Ag paste. In the Ag paste, oxide glass frits were totally replaced by Al85Ni5Y8Co2, Al-based metallic glass (MG) ones. The thermoplastic forming of the MG in the super cooled liquid region led to large contact area at the interface between Ag electrodes and Si layers and thus to specific contact resistance (ρc) as low as 0.86 mࡎ cm2. The specific contact resistance was a function of both contact area and thickness of the interlayer formed at the interface working as a tunneling barrier. [ABSTRACT FROM AUTHOR]

Tunnel oxide passivated contact (TOPCon) solar cells are key emerging devices in the commercial silicon-solar-cell sector. It is essential to have a suitable bottom cell in perovskite/silicon tandem solar cells for commercial use, given that good candidates boost efficiency through increased voltage. This is due to low recombination loss through the use of polysilicon and tunneling oxides. Here, a thin amorphous silicon layer is proposed to reduce parasitic absorption in the near-infrared region (NIR) in TOPCon solar cells, when used as the bottom cell of a tandem solar-cell system. Lifetime measurements and optical microscopy (OM) revealed that modifying both the timing and temperature of the annealing step to crystalize amorphous silicon to polysilicon can improve solar cell performance. For tandem cell applications, absorption in the NIR was compared using a semitransparent perovskite cell as a filter. Taken together, we confirmed the positive results of thin poly-Si, and expect that this will improve the application of perovskite/silicon tandem solar cells. [ABSTRACT FROM AUTHOR]

Abstract: Optoelectronic properties of hybrid solar cells were investigated by mixing cadmium sulfide nanorods with a conjugated polymer, poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). CdS nanorods were grown vertically on Ti substrates by electrochemical deposition through a porous alumina template. Absorption spectrum of the composite layer was the same as the superposition of the absorption spectrum of each individual material. The photoluminescence signal from MEH-PPV film was reduced as a result of the mixing. The energy conversion efficiency of MEH-PPV solar cell improved from 0.0012% to about 0.60% when combined with the vertically aligned CdS nanorods. [Copyright &y& Elsevier]

The potential-induced degradation (PID) mechanism in Cu(In,Ga)(Se,S)2 (CIGS) thin-film solar cells, which are alternative energy sources with a high efficiency (>23%) and upscaling possibilities, remains unclear. Therefore, the cause of PID in CIGS solar cells was investigated in this study at the cell level. First, an appropriate PID experiment structure at the cell level was determined. Subsequently, PID and recovery tests were conducted to confirm the PID phenomenon. Light current–voltage (I–V), dark I–V, and external quantum efficiency (EQE) analyses were conducted to determine changes in the cell characteristics. In addition, capacitance–voltage (C–V) measurements were carried out to determine the doping concentration and width of the space charge region (SCR). Based on the results, the causes of PID and recovery of CIGS solar cells were explored, and it was found that PID occurs due to changes in the bulk doping concentration and built-in potential at the junction. Furthermore, by distinguishing the effects of temperature and voltage, it was found that PID phenomena occurred when potential difference was involved. [ABSTRACT FROM AUTHOR]

Monolithic perovskite–silicon tandem solar cells with MoOx hole selective contact silicon bottom solar cells show a power conversion efficiency of 8%. A thin 15 nm-thick MoOx contact to n-type Si was used instead of a standard p+ emitter to collect holes and the SiOx/n+ poly-Si structure was deposited on the other side of the device for direct tunneling of electrons and this silicon bottom cell structure shows ~15% of power conversion efficiency. With this bottom carrier selective silicon cell, tin oxide, and subsequent perovskite structure were deposited to fabricate monolithic tandem solar cells. Monolithic tandem structure without ITO interlayer was also compared to confirm the role of MoOx in tandem cells and this tandem structure shows the power conversion efficiency of 3.3%. This research has confirmed that the MoOx layer simultaneously acts as a passivation layer and a hole collecting layer in this tandem structure. [ABSTRACT FROM AUTHOR]

The etching of Si wafers significantly influences the efficiency of photovoltaic devices. Texturing can effectively decrease front surface reflection and improve device performance. Saw damage removal (SDR) is necessary to yields uniform random pyramidal surfaces without the appearance of saw marks, it entails significant consumption of chemical solutions and complicated cleaning steps. Herein, an alternative process of pre-texturing thermal treatment was carried out at 800 °C for 10 min, followed by anisotropic texturing, and a uniform pyramidal surface over a large area of the textured surface was obtained without saw marks. Compared with that of as-cut mono-Si wafers (30.7%), the weighted average reflectance of the samples textured with or without thermal treatment decreased to 11.2% and 11.9%, respectively, and further to 3% and 3.4%, respectively, when anti-reflection coatings were applied. In addition, saw marks on the wafer surface were used as gettering sites during thermal treatment, and the bulk lifetime was more than doubled from 42.6 µs before the treatment to 93.8 µs after. The simple, SDR-free method presented herein for enhancing the textural uniformity of Si wafers and, hence, solar cell performance, can be employed on an industrial scale without necessitating additional investment in equipment. [ABSTRACT FROM AUTHOR]

Since the temperature of a photovoltaic (PV) module is not consistent as it was estimated at a standard test condition, the thermal stability of the solar cell parameters determines the temperature dependence of the PV module. Fill factor loss analysis of crystalline silicon solar cell is one of the most efficient methods to diagnose the dominant problem, accurately. In this study, the fill factor analysis method and the double-diode model of a solar cell was applied to analyze the effect of J01, J02, Rs, and Rsh on the fill factor in details. The temperature dependence of the parameters was compared through the passivated emitter rear cell (PERC) of the industrial scale solar cells. As a result of analysis, PERC cells showed different temperature dependence for the fill factor loss of the J01 and J02 as temperatures rose. In addition, we confirmed that fill factor loss from the J01 and J02 at elevated temperature depends on the initial state of the solar cells. The verification of the fill factor loss analysis was conducted by comparing to the fitting results of the injection dependent-carrier lifetime. [ABSTRACT FROM AUTHOR]

Ultra‐lightweight CdTe thin film solar cells in space: The cover image depicts ultra‐lightweight thin‐film cadmium telluride (CdTe) solar cells as applied to the solar panels that power satellites. In the space environment, there are various radiation sources such as energetic particles and solar flares. Thus, solar cells that are robust to radiation are necessary for performing tasks in space successfully. Among various solar cell materials, CdTe thin films have the intrinsic radiation hardness suitable for aerospace applications. This work demonstrates robust and stable CdTe thin film solar cells on ultra‐thin glass substrates. The cell secured its high specific power even after severe proton irradiation. High radiation hardness makes these CdTe solar cells feasible for long‐term space missions. More details can be found in the Full Paper by G. Yang and E. Cho et al. from Korea University on page 1463 in Issue 11, 2016 (DOI: 10.1002/ente.201600346). [ABSTRACT FROM AUTHOR]

• Optimization of optical/electrical effects in 2-terminal tandem structures. • Layer properties discussed to minimize optical loss using optical simulations. • Each bottom Si structure electrically simulated. • Characteristics of Si bottom cells identified according to bulk properties. • Potential efficiency limit evaluated; method to improve cell performance proposed. Two-terminal perovskite/silicon (Si) tandem solar cells have made significant progress in terms of efficiency and are considered suitable candidates for the next generation of photovoltaic devices. However, research on Si bottom cell optimization is limited, with optimization being conducted only within a specific structure reported as high efficiency. To present more general and higher efficiency possibilities, optimization is necessary not only for the perovskite and interlayer but also for each bottom Si solar cell structure. In this study, we proposed a numerical modeling approach for analyzing and optimizing the effects of optical and electrical properties in 2-terminal tandem structures. First, the properties for each layer were discussed to minimize optical loss using optical simulations, considering the recently reported high-efficiency 2-terminal perovskite/Si tandem system. After fixing the top perovskite and recombination layer using these properties, each bottom Si structure, which is divided into homojunction (PERC and TOPCon structure) and heterojunction (HIT structure), was electrically simulated. The characteristics of Si bottom cells were identified based on bulk properties (bulk lifetime and resistivity). Consequently, we proposed an improvement method and structure capable of achieving maximum possible efficiency of more than 30 % as a tandem device for each bottom cell structure. [ABSTRACT FROM AUTHOR]

• Removal of byproducts and plasma damage layers caused by reactive ion etching. • Calculation of short circuit current density considering weighted average reflectance. • Maintains low reflectance after damage removal etching and increases efficiency of multi-crystalline silicon solar cells. As part of the surface texturing process of multi-crystalline silicon solar cells, isotropic etching is performed by using an acidic solution. Furthermore, metal catalyst chemical etching (MCCE), reactive ion etching (RIE), and laser etching are used to further decrease surface reflectance. This study aimed to increase the power conversion efficiency of the solar cell by improving the short-circuit current density (J sc) using MCCE and RIE. During RIE, a byproduct and a plasma damage layer are formed on the silicon surface, which decrease the efficiency of the solar cell and therefore need to be identified and effectively removed. Transmission electron spectroscopy, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy analyses were performed to identify the byproducts formed during RIE to confirm that it was amorphous silicon oxide. Furthermore, an etching process using acidic and alkaline base solutions was used to remove the plasma damage layer and the J sc loss was calculated using the reflectance. As a results, confirm a difference of up to ∼ 1.6 mA/cm2, and an improvement of approximately 0.6% was observed in the solar cell efficiency. These results show a method of minimizing J sc loss and removing surface damage in a silicon solar cells fabricated using the RIE method. [ABSTRACT FROM AUTHOR]

Abstract: CdTe thin film was successfully grown on GaN/Sapphire substrate using a close spaced sublimation (CSS) system for the applications in solar cells. CdTe thin film was characterized by SEM, micro-Raman spectroscopy, and X-ray diffraction. The growth rate was 1μm/min. In addition, we confirmed that CdCl2 treatment beneficially influenced the structure and composition of the CdTe thin films. CdCl2 treatment which has been known that it improved the efficiency of the CdS/CdTe solar cells, produced similar positive effects such as increasing the CdTe grain size and reducing the number of pin-holes. The growth of the CdTe thin film by CSS method produced nominal effects on biaxial strain and carrier concentrations in the GaN/Sapphire substrate. The CdTe thin film grown on the GaN/Sapphire substrate holds great promise for use in solar cell applications due to its several advantages. [Copyright &y& Elsevier]

Abstract: We fabricated point-contacted a-Si:H(p)/c-Si(n) heterojunction solar cells using patterned SiO2 and investigated their electrical properties using the light current–voltage (I–V) curve and Suns-Voc measurements. The light I–V curves showed bias-dependent changes according to the applied voltage in the point-contacted cells, especially in the samples with a long distance between the point-contacted junctions. The Suns-Voc measurements showed that the bias-dependence of the light I–V curves did not originate from the recombination in the SiO2/Si or a-Si:H(p)/c-Si(n) interface, but from the series resistances. It is possible to explain the bias-dependent light I–V curve in terms of the conductivity of a-Si:H(p) and difference in the electrical contact properties between a-Si:H(p), ZnO and c-Si(n). These results mean that the electrical properties of the a-Si:H(p) layer and the contact properties with this layer are also critical to obtain a high Jsc and fill factor in n-type based Si heterojunction solar cells. [Copyright &y& Elsevier]

Abstract: As an effective method of increasing its total conversion efficiency, the protective layer of solar cells was patterned with a nano-sized moth-eye structure. This pattern with its special shape and size serves as an anti-reflective layer. To form a pattern on the PVC film, the hot-embossing method was used. Moreover, a polyvinyl chloride (PVC) film patterned on both sides was also fabricated to improve the performance of anti-reflection functionality. A solar cell with a patterned PVC film as a protective layer exhibited higher quantum efficiency and total conversion efficiency than a solar cell with a bare PVC film as a protective layer. [Copyright &y& Elsevier]

Abstract: Organic photovoltaic cells have important advantages, such as low cost and mechanical flexibility. The conducting polymer poly(3,4 ethylenedioxy-thiophene):poly(styrene sulfonate) (PEDOT:PSS) has been widely used as an interfacial layer or a polymer electrode in polymer electronic devices, such as photovoltaic devices and light-emitting diodes. In this report, we discuss the direct current (DC) conductivity of PEDOT:PSS films containing various weight ratios of sorbitol dopant. The work function is shown to steadily decrease with increasing dopant content. With different dopant contents, illuminated current–voltage photovoltaic characteristics were observed. Ultraviolet photoelectron spectroscopy (UPS) analysis revealed that the work function of the PEDOT:PSS was affected by its sorbitol content. The morphologies of the doped PEDOT:PSS films were characterized by atomic force microscopy (AFM). For the device fabrication, we made organic photovoltaic cells by a spin-coating process and Al deposition by thermal evaporation. The sorbitol dopant is able to improve the efficiency of the device. [Copyright &y& Elsevier]

Abstract Silicon nitride (SiNx:H) films are generally used as passivation and anti-reflection layers in solar cells, and they are usually made by plasma-enhanced chemical vapor deposition (PECVD). Silicon nitride could act as a hydrogen diffusion source, and it also plays a role in chemical passivation. In this study, we investigated the improvement of the passivation characteristics of the passivated contact structure by a PECVD SiNx:H hydrogenation process and the characteristics of SiNx:H for improving the passivation characteristics. It was confirmed that the passivation characteristics cannot be predicted only by the mass density of the SiNx:H film, and the chemical bonding ratio in the SiNx:H thin film is also important. In addition, higher passivation characteristics can be obtained when SiNx:H thin films with higher S H bond concentration and dominant N 2 Si H 2 bonds are used. Highlights • SiNx:H thin film is used a hydrogenation source for the passivated contact structure. • Passivation depends on Si H and N H bond ratios of SiNx:H films at similar densities. • Si H bonding, especially N 2 Si-H 2 bonding, in SiNx:H films contributes to passivation. [ABSTRACT FROM AUTHOR]

Abstract We investigated strontium oxide (SrO) as an interlayer material to enhance the UV stability of a CH 3 NH 3 PbI 3 perovskite solar cell. Moisture and over 400 nm wavelength of light were excluded to investigate the effect of UV light only. Two different interlayer fabrication processes were examined to optimize the performance of this solar cell. Devices fabricated by dipping for 30 min in SrO solution exhibited photoconversion efficiencies of 15.5%, whereas those fabricated with 60-min dipping showed photoconversion efficiencies of 15% and exhibited local Sr agglomeration. Devices with SrO displayed lower initial efficiencies than those without any SrO layer (17.6%), However, a device without SrO retained only 34.4% of its initial efficiency after 100 h of UV exposure. In contrast, SrO-incorporated devices retained almost 60.0% of their initial efficiency. Severe μ-PL mapping intensity degradation was observed in devices that did not include the interlayer, but no degradation was observed in those with the SrO interlayer. This can be attributed to the passivation of the degradation sites by SrO. Graphical abstract Image 1 Highlights • Perovskite UV stability was tested under conditions except moisture, oxygen and wavelengths exceeding 400 nm. • With high resolution μ-PL mapping technique, direct evidence is provided about the area perovskite UV degradation begins. • UV degradation is initiated at the ETL/perovskite interface. • Effect of the SrO interlayer on UV stability was examined in an inert atmosphere. • UV stability is enhanced by SrO interface passivation. [ABSTRACT FROM AUTHOR]

To ensure of the fabrication crystalline Si (c-Si) solar cells at affordable costs, research has been actively conducted on the use of Cu-based pastes as alternatives to their Ag counterparts, which are currently being used as front electrode materials. However, only limited studies have reported on the use of Cu pastes in processes involving high-temperature firing, primarily owing to the issues caused by Cu oxidization and the resulting products acting as deep-level impurities. In this study, the applicability and limitations of Cu-based pastes containing Cu–Ag core–shell particles as the front electrodes of Si solar cells were investigated. A double printing structure with a seed layer of Ag paste was adopted to prevent direct contact between Si and Cu. By analyzing the morphological and electrical properties, the O-mediated electrode-formation mechanism of the Cu-based paste during high-temperature firing under ambient air conditions was evaluated and compared with that of the conventional Ag paste. The electrical parameters of c-Si solar cells were found to always deteriorate when the Cu paste was used, regardless of the electrode structure, owing to the reduction of Cu involved in Ag crystallite formation. Moreover, only contact formation under inert ambient conditions presented electrical parameters similar to those for commercial Ag paste when using high-temperature firing. Finally, the limitations of applying a front electrode paste primarily containing Cu were assessed. • The applicability and limitations of Cu-based paste in Si solar cells were studied. • Characteristics of this paste were compared with those of conventional Ag paste. • O-mediated electrode formation mechanism of Cu-based paste was evaluated. • This study will promote the production of competitive crystalline Si solar cells. [ABSTRACT FROM AUTHOR]

Silicon oxynitride (SiON) could be used in combination with silicon nitride (SiN) to form a multilayer anti-reflection coating on the front side of selective emitter solar cells. In this study, these double anti-reflection layers were fabricated by a continuous deposition technique using the plasma enhanced chemical vapor deposition method. We attempted to determine whether this method is fast and cost effective and can achieve higher efficiency for solar cell manufacture. The results show that the short circuit current density for the double layer anti-reflection coating on selective emitter solar cells was higher by 0.5 mA/cm 2 compared to the single layer coating owing to the improved optical reflectance. The incorporation of a SiN/SiON stack into the anti-reflection layer of the CZ selective emitter solar cells yields an energy conversion efficiency of 19.4%, which is higher than the efficiency (19.18%) for the reference solar cells with single layer SiN anti-reflection coating. [ABSTRACT FROM AUTHOR]

In conventional sequential deposition, PbI 2 -free CH 3 NH 3 PbI 3 perovskite films can be achieved when the PbI 2 substrate reacts with a relatively low-concentration CH 3 NH 3 I solution (<8 mg of CH 3 NH 3 I per 1 mL of IPA) but the film that is formed has only sparse and uneven coverage. On the other hand, a dense CH 3 NH 3 PbI 3 perovskite film can be formed on a mesoporous TiO 2 substrate when the PbI 2 substrate reacts with a relatively high-concentration MAI solution (>8 mg of CH 3 NH 3 I per 1 mL of IPA), but unreacted PbI 2 is still present in CH 3 NH 3 PbI 3 layer in such cases. Here, we developed organic-inorganic perovskite solar cells with high efficiency by preparing dense and PbI 2 -free films using a modified sequential deposition process. By utilizing the reaction behavior between PbI 2 and MAI, solar cells with an average power-conversion efficiency of 15.1% and high reproducibility and stability were achieved. [ABSTRACT FROM AUTHOR]

We demonstrate production of high-quality Cu(InGa)(SSe) 2 (CIGSSe) films by high-rate supersonic spray deposition. This technique is unique in creating particle-based films without introducing impurities, because no additives or binders are used. The thin film deposition process was investigated computationally, to understand the pulverization of the incoming particles. These simulations were consistent with experimental observations. Grain growth was improved by adding a 300-nm copper layer atop the CIGSSe film; selenization of the resulting bilayer produced a CuSe liquid flux that assisted the sintering process. The final CIGSSe film-based solar cell had a conversion efficiency of 5.49% with J sc = 18.73 mA/cm 2 , V oc = 0.488 V, and FF = 59.99% in an active area of 0.44 cm 2 . [ABSTRACT FROM AUTHOR]

The purpose of this work is to investigate a back surface field (BSF) at a number of wafer resistivities for industrial crystalline silicon solar cells. As indicated in this manuscript, doping a crucible-grown Czochralski (Cz)-Si ingot with Ga offers a sure way of eliminating light-induced degradation (LID) because LID is composed of B and O complex. However, the low segregation coefficient of Ga in Si causes a much wider resistivity variation in the Ga-doped Cz-Si ingot. This resistivity variation in a Cz-Si wafer at different locations varies the performance, as is already known. In the light of a B-doped wafer, we made wider resistivity in Si ingot; we investigated how resistivities affect the solar cell performance as a function of BSF quality. [ABSTRACT FROM AUTHOR]

The temperature variation of solar cells due to white bias light irradiation during the spectral responsivity measurement and its effect on the spectral responsivity measurement result were investigated for various types of solar cells, such as crystalline silicon (c-Si), Cu(In,Ga)Se 2 (CIGS), and dye-sensitized solar cells (DSSCs). For the investigation, a spectral responsivity measurement system, which can employ the well-known sample temperature control methods (such as the “temperature controlled sample stage” method and the “forced air cooling” method) has been used. Hence, the availability of these sample temperature control methods has also been tested. Through the investigation, it was found that the actual temperature of the solar cells located under the AM1.5G-approximated white bias light can be increased significantly during the spectral responsivity measurement, depending on the sample temperature control methods applied. In addition, it was also found that the increase of sample temperature can lead to a significant error in the measured spectral responsivity, depending on the types of solar cells being measured. In addition, a simple analytic model based on the classical heat transfer theory was developed to understand the temperature variation of the solar cells under the spectral responsivity measurement environment. [ABSTRACT FROM AUTHOR]

Most boron diffusion technologies result in the formation of an undesirable boron-rich layer (BRL) on the emitter surface. This paper reports on a study of the impact of gradual etching of the BRL on n-type silicon solar cell performance. It is found that gradual removal of the BRL improves surface passivation and bulk lifetime in the finished cell, while over-etching of the BRL results in a sharp decrease in fill factor due to the increased n-factor and series resistance. It is shown that the optimum chemical etching of the BRL formed as a byproduct of the screen-printed boron emitter diffusion used in this study raised the cell efficiency by ~0.5%, resulting in 20.0% efficient large area (239 cm 2 ) n-type solar cells. The change in BRL thickness and morphology as a function of chemical etching time was investigated by TEM and AES measurements to explain the quantitative impact of BRL removal on cell performance. [ABSTRACT FROM AUTHOR]

Al2O3 layers fabricated with atomic layer deposition (ALD) show high levels of surface passivation on p- and n-type silicon wafers. In order to form front and rear electrodes, Al2O3 layers should undergo a firing process at a high peak temperature. Therefore, the Al2O3 layer must be stable under these conditions to maintain a high level of surface passivation during the firing process. In this study, Al2O3 layers fabricated with ALD were pre-annealed to enhance their thermal stability during the firing process. From quasi-steady state photoconductance (QSSPC) measurements, the difference between the implied Voc values of the pre-annealed and fired samples was found to be smallest (3 mV) when the sample was pre-annealed at 620 °C. The surface recombination rate calculated from capacitance-voltage ( C- V) measurements of metal-Al2O3-Si (metal-insulator-semiconductor) structures was shown to be low when the sample was pre-annealed at 600-650 °C. Thus, firing stability was achieved with pre-annealing at 620 °C by reducing the surface recombination rate. We conclude that it is necessary to pre-anneal the Al2O3 passivation layer at this specific temperature to reduce the degradation of the passivation quality of Al2O3 after the firing process. [ABSTRACT FROM AUTHOR]

Effective contact formation during low-temperature firing with applied current was investigated in this study. The screen-printed electrode was fired using rapid thermal annealing and contacted by etching the passivation layer and forming Ag crystallites. In our previous study, we proposed a method for reducing this contact resistance from 5 to 1 mΩ cm2 by applying a current during the firing of a phosphorous-doped (P-doped) n+ emitter in a p-type Si wafer without a silicon nitride (SiN x) passivation layer. According to the results, current application during the firing of Si solar cells should reduce the required firing temperature. Herein, a current (3 A) was applied between the screen-printed electrode and P-doped n+ emitter in a p-type Si wafer with an SiN x passivation layer during low-temperature firing from 350 to 600 °C. The major effects of the proposed methods were a reduced contact resistance and enhanced of SiN x etching. Cross-sectional scanning electron microscopy images at different firing temperatures demonstrated that current injection during firing promoted the etching of the SiN x layer. Additionally, the method of current injection with low-temperature firing proposed in this work resulted in a device with a solar cell efficiency of 19.0%, which is similar to the efficiency of a reference cell fired at a higher temperature. • This study is a paper on the metallization using current injection at low-temperature firing and their effect on the contact formation. • The enhanced SiN x etching reaction for crystalline Si (c-Si) solar cells metallization was proposed by a low-temperature firing process via current injection. • A power conversion efficiency (PCE) of 19.0% was achieved via a low-temperature (500 °C) firing process with the current injection. [ABSTRACT FROM AUTHOR]