We use solar cell capacitance simulator-1D to simulate a fabricated inverted perovskite solar cell. The perovskite solar cell employs solution-processed inorganic hole and electron transfer layers. According to our simulations, surface defect densities at the interfaces of the perovskite active layer and inorganic hole/electron transfer materials in solution-based fabrication method are two orders of magnitude greater than that in the vapor deposition fabrication method. Increase of the surface defect densities reduces the circuit current, fill factor, and power conversion efficiency.

Among the methods to prepare hybrid organic–inorganic perovskite films, the intramolecular exchange method was the first one that made possible to prepare perovskite solar cells with efficiencies higher than 20%. However, perovskite formation by this method is not completely understood, especially in ambient conditions. In this work, perovskite films were prepared by the intramolecular exchange method in ambient conditions. The spin coating speed and the frequency of the MAI solution dripping onto PbI2(DMSO) were varied during the deposition steps. With the combination of these two parameters, a rigid control of the solvent drying was possible. Thus, depending on the chosen conditions, the intermediate (MA)2Pb3I8·2DMSO was formed with residual PbI2. Otherwise, direct formation of perovskite film was attained. A mechanism for the direct formation of bulk perovskite was proposed. We also investigated how the posterior thermal annealing affects the crystallinity and defects in perovskite films. With prolonged thermal annealing, the excess of MAI can be avoided, increasing the efficiency and decreasing the hysteresis of the solar cells. The best perovskite solar cell achieved a stabilized power output of 12.9%. The findings of this work pave the way for realizing the fabrication of efficient perovskite solar cells in ambient atmosphere, a very desirable condition for cost-efficient large scale manufacturing of this technology.

We use facile coating techniques including spray coating and drop casting to fabricate methylammonium lead iodide perovskite solar cells through a two-step sequential deposition approach. In the first step, for the deposition of the lead iodide, spray coating substitutes for the commonly used lab-scale spin coating, while the operating parameters of the former process are optimized to achieve a fully covered and uniform film of lead iodide. In the second step, to deposit methylammonium iodide atop the lead iodide layer to form methylammonium lead iodide perovskite, dip-coating process is replaced by the touch-free drop casting and scalable pulsed-spray coating. It is found that the performance of the perovskite films and devices made by pulsed-spray coating and drop casting is similar to those prepared by dip coating, while the large-scale production capabilities of such methods beside the low material consumptions of drop casting prove their potential to replace dip coating in large-scale manufacturing of perovskite solar cells. The champion devices fabricated by spray-drop and spin-drop techniques demonstrated power conversion efficiencies of 6.92% and 9.48%, respectively. It is expected that device fabrication in a low-humidity environment using the optimized parameters and optimization of other layers will result in higher efficiencies.

Four-junction solar cells for space and terrestrial applications require a junction with a band gap of <inline-formula< <mml:math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML"< <mml:mrow< <mml:mo form="prefix"<∼</mml:mo< <mml:mn<1</mml:mn< <mml:mtext<  </mml:mtext< <mml:mi<eV</mml:mi< </mml:mrow< </mml:math< </inline-formula< for optimal performance. InGaAsN or InGaAsN(Sb) dilute nitride junctions have been demonstrated for this purpose, but in achieving the <inline-formula< <mml:math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML"< <mml:mrow< <mml:mn<14</mml:mn< <mml:mtext<  </mml:mtext< <mml:mi<mA</mml:mi< <mml:mo stretchy="false"</</mml:mo< <mml:msup< <mml:mrow< <mml:mi<cm</mml:mi< </mml:mrow< <mml:mrow< <mml:mn<2</mml:mn< </mml:mrow< </mml:msup< </mml:mrow< </mml:math< </inline-formula< short-circuit current needed to match typical GaInP and GaAs junctions, the open-circuit voltage (<inline-formula< <mml:math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML"< <mml:mrow< <mml:msub< <mml:mrow< <mml:mi<V</mml:mi< </mml:mrow< <mml:mrow< <mml:mi<OC</mml:mi< </mml:mrow< </mml:msub< </mml:mrow< </mml:math< </inline-formula<) and fill factor of these junctions are compromised. In multijunction devices incorporating materials with short diffusion lengths, we study the use of thin junctions to minimize sensitivity to varying material quality and ensure adequate transmission into lower junctions. An <inline-formula< <mml:math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML"< <mml:mrow< <mml:mi<n</mml:mi< <mml:mtext<-</mml:mtext< <mml:mi<i</mml:mi< <mml:mtext<-</mml:mtext< <mml:mi<p</mml:mi< </mml:mrow< </mml:math< </inline-formula< device with <inline-formula< <mml:math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML"< <mml:mrow< <mml:mn<0.65</mml:mn< <mml:mtext<-</mml:mtext< <mml:mi<μ</mml:mi< <mml:mi mathvariant="normal"<m</mml:mi< </mml:mrow< </mml:math< </inline-formula< absorber thickness has sufficient short-circuit current, however, it relies less heavily on field-aided collection than a device with a <inline-formula< <mml:math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML"< <mml:mrow< <mml:mn<1</mml:mn< <mml:mtext<-</mml:mtext< <mml:mi<μ</mml:mi< <mml:mi mathvariant="normal"<m</mml:mi< </mml:mrow< </mml:math< </inline-formula< absorber. Our standard cell fabrication process, which includes a rapid thermal anneal of the contacts, yields a significant improvement in diffusion length and device performance. By optimizing a four-junction cell around a smaller 1-sun short-circuit current of <inline-formula< <mml:math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML"< <mml:mrow< <mml:mn<12.5</mml:mn< <mml:mtext<  </mml:mtext< <mml:mi<mA</mml:mi< <mml:mo stretchy="false"</</mml:mo< <mml:msup< <mml:mrow< <mml:mi<cm</mml:mi< </mml:mrow< <mml:mrow< <mml:mn<2</mml:mn< </mml:mrow< </mml:msup< </mml:mrow< </mml:math< </inline-formula<, we produced an InGaAsN(Sb) junction with open-circuit voltage of 0.44 V at 1000 suns (<inline-formula< <mml:math display="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML"< <mml:mrow< <mml:mn<1</mml:mn< <mml:mtext<  </mml:mtext< <mml:mtext<sun</mml:mtext< <mml:mo<=</mml:mo< <mml:mn<100</mml:mn< <mml:mtext<  </mml:mtext< <mml:mi<mW</mml:mi< <mml:mo stretchy="false"</</mml:mo< <mml:msup< <mml:mrow< <mml:mi<c

A 29.5% efficient perovskite/SiC passivated interdigitated back contact silicon heterojunction (IBC-SiHJ) mechanically stacked tandem solar cell device has been designed and simulated. This is a substantial improvement of 40% and 15%, respectively, compared to the transparent perovskite solar cell (21.1%) and Si solar cell (25.6%) operated individually. The perovskite solar cell has been used as a top subcell, whereas 250- and 25-μm-thick IBC-SiHJ solar cells have been used as bottom subcells. The realistic technology computer aided design analysis has been performed to understand the physical processes in the device and to make reliable predictions of the behavior. The performance of the top subcell has been obtained for different acceptor densities and hole mobility in Spiro-MeOTAD along with the impact of counter electrode work function. To incorporate the effect of material quality, the influence of carrier lifetimes has also been studied for perovskite top and IBC-SiHJ bottom subcells. The optical and electrical behavior of the devices has been obtained for both standalone as well as tandem configuration. Results reported in this study reveal that the proposed four-terminal tandem device may open a new door for cost-effective and energy-efficient applications.

We fabricated (n) c-Si/ (p) GaAs heterojunctions, by combining low temperature (∼175°C) RF-PECVD for Si and metal organic vapor phase epitaxy for GaAs, aiming at producing hybrid tunnel junctions for Si/III-V tandem solar cells. The electrical properties of these heterojunctions were measured and compared to that of a reference III-V tunnel junction. Several challenges in the fabrication of such heterostructures were identified and we especially focused in this study on the impact of atomic hydrogen present in the plasma used for the deposition of silicon on p-doped GaAs doping level. The obtained results show that hydrogenation by H2 plasma strongly reduces the doping level at the surface of the GaAs:C grown film. Thirty seconds of H2 plasma exposition at 175°C are sufficient to reduce the GaAs film doping level from 1×1020  cm−3 to <1×1019  cm−3 at the surface and over a depth of about 20 nm. Such strong reduction of the doping level is critical for the performance of the tunnel junction. However, the doping level can be fully recovered after annealing at 350°C.

The authors investigate the efficiency of a series of broadband rectennas designed to harvest the free-propagating electromagnetic energy at terahertz frequencies. We analyze by simulations the case of self-complementary square- and Archimedean-spiral antennas coupled to L-shaped self-switching diodes (L-SSDs). First, the geometry (i.e., the width and length of the channel) of the L-SSD was optimized to obtain a remarkable diode-like I–V response. Subsequently, the optimized L-SSD geometry was coupled to both types of spiral antennas and their characteristic impedance was studied. Finally, the energy conversion efficiency was evaluated for both rectenna architectures.

The development of a system for output power estimation and fault detection in photovoltaic (PV) modules using an artificial neural network (ANN) is presented. Over 30,000 healthy and faulty data sets containing per-minute measurements of PV module output power (W) and irradiance (W/m2) along with real-time calculations of the Sun’s position in the sky and the PV module surface temperature, collected during a three-month period, are fed to different ANNs as training paths. The first ANN being trained on healthy data is used for PV module output power estimation and the second ANN, which is trained on both healthy and faulty data, is utilized for PV module fault detection. The proposed PV module-level fault detection algorithm can expectedly be deployed in broader PV fleets by taking developmental considerations. The machine-learning-based automated system provides the possibility of all-sky real-time monitoring and fault detection of PV modules under any meteorological condition. Utilizing the proposed system, any power loss caused by damaged cells, shading conditions, accumulated dirt and dust on module surface, etc., is detected and reported immediately, potentially yielding increased reliability and efficiency of the PV systems and decreased support and maintenance costs.

A significant part of broad band sunlight remains unabsorbed in a simple structured amorphous silicon solar cell. This absorption can be enhanced by adopting a light-trapping scheme with the help of a textured front surface and back reflector. For this purpose, honeycomb-type texture was fabricated on a glass surface by chemical etching. A 3  μm×3  μm honeycomb patterned optical-mask was used to create an image-pattern of an etch-mask on the glass surfaces. We used 0.5% hydrofluoric acid (HF) as an etchant solution with an optimized etching time ranging between 25 and 28 min. This single textured glass shows an enhancement in diffused transmission of light. In solar cell application, a 630-nm-thick Al-doped ZnO (AZO) layer was deposited over the textured glass surface. An additional random etching was carried out on the AZO with 1% HF acid solution for 10 s. This results to a double textured AZO superstrate on which solar cells were fabricated. The solar cells show higher short circuit current density to 17.2  mA/cm2. Finally, we obtained photovoltaic conversion efficiency of an optimized solar cell as 10.75% (with the corresponding Jsc as 17.03  mA/cm2).

In vitro grown shoots cultures (Prunus salicina × Prunus persica), elicited by methyl jasmonate (MJ), are reported here for the first time to prepare a natural dye for dye-sensitized solar cells (DSSC). Redox properties of the dye, its photostability, and light absorption properties suggested it as a candidate as natural photosensitizers for TiO2 photoelectrodes. Redox properties of the dye influence the DSSC production of photocurrent, thus three antioxidant assays were performed in order to characterize the antioxidant potential of this dye. The dye exhibited a high antioxidant activity in all the assays performed. Photostability assay revealed that the dye was quite stable to light. The power conversion efficiency that we obtained (0.53%) was comparable to the data by other authors with anthocyanins-based dyes from in vivo grown plants. Finally, we compared the dye with the partially purified one as photosensitizer in DSSC. The results indicated that the raw pigment from in vitro shoot cultures of P. salicina × P. persica elicited with MJ can be proposed without the needing of any other chemicals, thermal or purification process, or pH adjustments, as a dye for natural sensitized solar cells.

Zinc oxide nanoparticles (ZnO NPs) were synthesized using a hydrothermal route. The prepared ZnO NPs were characterized by x-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), UV–vis spectroscopy, and photoluminescence (PL) spectroscopy. The XRD patterns confirmed the standard hexagonal wurtzite structure of ZnO NPs, and the calculated value of the average particle size was 23.34 nm. HR-TEM micrographs of ZnO NPs showed semispherical particle morphologies and their sizes lie between 10 and 40 nm. The estimated average size distribution of ZnO NPs was 21.35 ± 6.01    nm . UV–vis spectrum of ZnO NPs revealed the highest absorption band at 360.5 nm, and the E g was 3.70 ± 0.01    eV . The PL spectrum emission was deconvoluted by eight peaks into two regions [near-ultraviolet (NUV) and visible that caused from the defects]. Two groups of dye-sensitized solar cells (DSSCs) thin film devices based on ZnO NPs were sensitized in different concentration solutions of 0.1, 0.32, and 0.5 mM of eosin B (EB) and eosin Y (EY) dyes. The sensitized DSSCs device with 0.32-mM dye of EY displayed higher efficiency and its performance parameters are much better among all other fabricated DSSCs devices. The short current density ( J sc ) increased from 1.59 to 4.97   mA / cm 2 and the V oc enhanced from 0.36 to 0.46 V. The conversion efficiency from light to electricity showed a significant improvement from 0.29% to 0.94%. The transient open circuit photovoltage decay (TOCPVD) was measured to estimate the apparent electron lifetime or response time ( τ n ) or the electron recombination rate ( k