Lead-free perovskite layers may provide a good alternative to the commonly used lead-halide-based perovskite absorber layers in photovoltaics. Energy level alignment of the active semiconductor with contact layers is a key factor in device performance. Kelvin probe force microscopy was used during vapor deposition of C60 onto formamidinium tin iodide to investigate contact formation with detailed local resolution of these materials that are significant for photovoltaic cells. Significant differences dependent on the growth rate of C60 were detected. Sufficiently high deposition rates were essential to reach compact C60 films needed for good contact. A space charge layer larger than 90 nm within the C60 layer was established without indication of interfacial dipoles. The present analysis gives a clear indication of a well-functioning contact of fullerenes to formamidinium tin iodide that is suitable for the use in photovoltaic devices provided that thin compact fullerene films are formed.

The nitrogen-decorated CeO2/reduced graphene oxide nanocomposite (CeO2/N-rGO) was one-step synthesized by a facile hydrothermal technique and applied as counter electrode materials for dye-sensitized solar cells (DSSCs). For comparison, CeO2/rGO and rGO were also synthesized by adjusting corresponding reactants. It was found that the as-synthesized CeO2/N-rGO shows better electrocatalytic activity for triiodide/iodide reduction than that of pure rGO and CeO2/rGO, and a synergistic effect of nitrogen and CeO2 on the rGO sheets was observed. The photoelectric conversion efficiency of DSSCs based on CeO2/N-rGO counter electrode was 3.20%, which is higher than that of CeO2/rGO (2.45%) and rGO counter electrode (1.37%). Furthermore, the synergistic effect of nitrogen and CeO2 on the rGO sheets was also discussed in detail with different CeO2 amount levels. It is believed that this one-step synthetic method is a potential way to synthesize low-cost and efficient rGO-based multiple composited counter electrode materials to replace more expensive Pt.

Achieving control over the morphology of conjugated polymer (CP) blends at nanoscale is crucial for enhancing their performances in diverse organic optoelectronic devices, including thin film transistors, photovoltaics, and light emitting diodes. However, the complex CP chemical structures and intramolecular interactions often make such control difficult to implement. We demonstrate here that cooperative combination of non-covalent interactions, including hydrogen bonding, coordination interactions, and π-π interactions, etc., can be used to effectively define the morphology of CP blend films, in particular being able to achieve accurate spatial arrangement of nanoparticles within CP nanostructures. Through UV-vis absorption spectroscopy and transmission electron microscopy, we show strong attachment of fullerene molecules, CdSe quantum dots, and iron oxide nanoparticles, onto well-defined CP nanofibers. The resulting core/shell hybrid nanofibers exhibit well-defined donor/acceptor interface when employed in photovoltaic devices, which also contributes to enhanced charge separation and transport. These findings provide a facile new methodology of improving CP/nanoparticle interfacial properties and controlling blend morphology. The generality of this methodology demonstrated in current studies points to a new way of designing hybrid materials based on organic polymers and inorganic nanoparticles towards applications in modern electronic devices.

In the last years, perovskite solar cells have attracted great interest in photovoltaic (PV) research due to their possibility to become a highly efficient and low-cost alternative to silicon solar cells. Cells based on the widely used Pb-containing perovskites have reached power conversion efficiencies (PCE) of more than 20 %. One of the major hurdles for the rapid commercialization of perovskite photovoltaics is the lack of deposition tools and processes for large areas. Chemical vapor deposition (CVD) is an appealing technique because it is scalable and furthermore features superior process control and reproducibility in depositing high-purity films. In this work, we present a novel showerhead-based CVD tool to fabricate perovskite films by simultaneous delivery of precursors from the gas phase. We highlight the control of the perovskite film composition and properties by adjusting the individual precursor deposition rates. Providing the optimal supply of precursors results in stoichiometric perovskite films without any detectable residues.

A comparison between electrochemical carbon dioxide conversion and reforestation is presented. By comparing thermodynamic and forestry data, recommendations for technology development can be made.

With the global average temperature steadily increasing due to anthropogenic emission of greenhouse gases into the atmosphere, there has been increasing interest worldwide in new technologies for carbon capture, utilization, and storage (CCUS). This coincides with the decrease in cost of deployment of intermittent renewable electricity sources, specifically solar energy, necessitating development of new methods for energy storage. Carbon dioxide conversion technologies driven by photovoltaics aim to address both these needs. To adequately contribute to greenhouse gas reduction, the carbon dioxide conversion technology deployed should have a substantially higher rate of carbon dioxide removal than planting an equivalent-sized forest. Using consistent methodologies, we analyze the effectiveness of model photovoltaic-driven carbon dioxide conversion technologies that produce liquid alcohols as compared to planting an equivalent forest. This analysis serves to establish an energy use boundary for carbon dioxide conversion technology, in order to be a viable alternative as a net carbon negative technology.

Circular energy transformation of Turkey is essential to strengthen the national energy security. Turkey will benefit from moving towards a circular economy.

Circular economy (CE) has gained much attention due to global warming and climate change which are the most serious issues faced in the world. The United Nations has been struggling with the issues regarding sustainable development by releasing some programs and legislations, which are mostly supported by the EU. The EU's CE including both economy and energy within the scope of low-carbon world is binding for Turkey's energy transition. Among renewables, solar energy preserved the leading capacity expansion with an increase of 98 GW in 2019 in the world. Solar photovoltaic (PV) has become a mainstream energy source among renewables. Since the PV installation has been growing all around the world, several countries especially China, Germany, and the UK pay special attention to a sustainable PV waste management concept. We present the special case of Turkey within the global CE along with the current status of renewable energy in the global energy transformation. Turkey's energy outlook and the EU's targets are reviewed, and the significant role of solar energy in the CE transition process of Turkey has been revealed. We suggested adding a vision of “More Circular” to her new energy policy “More Domestic, More Renewable.”

This study reports on the effect of introducing TiO2 compact layer on the photovoltaic characteristics of TiO2/Nb2O5 composite dye sensitized solar cell. The compact layer was deposited by spray pyrolysis technique. It was observed that introduction of 60 nm thick compact layer improved the short circuit current density Jsc ,Open circuit voltage Voc, and efficiency of the cell from 4.9 mA/cm2 to 8.2 mA/cm2, 6.8×10-1 V to 7.2×10-1 V and 1.9 % to 3.4 % respectively compared to traditional cell prepared without compact layer. Electrochemical impedance spectroscopy confirmed an increase in recombination resistance from 5.5×101 Ω.cm2 for bare DSSC to 9.0×101 Ω.cm2 for DSSC with compact layer thereby improving electron lifetime of the cells from 2.5×10-4 s to 386.9×10-4 s.

In this work, lead halide perovskite photodetectors were fabricated by a laser-assisted rapid fabrication method. A microchannel was engraved on an indium tin oxide (ITO) coated polyethylene terephthalate (PET) conductive flexible substrate using a CO2 laser source. The channels were filled by methylammonium lead halide perovskite (CH3NH3PbI3) using the capillary motion of perovskite first-step method precursor. CYTOP and the low-cost commercially available FluroPel were used as a top protective coating layer to suppress the decomposition of the perovskite channel. X-ray diffraction pattern (XRD) was used to measure the stability of the perovskite. Strong humidity resistant and self-healing behavior were observed in both devices. The performance of the photodetectors was compared by measuring electrical and optical characteristics over time. This study will help in the low-cost fabrication of perovskite-based devices.

The electric industry is transitioning to higher penetrations of renewables. Hundred per cent renewable penetration is no longer a pipe dream. Rather than by doubling down on existing renewable technologies, we can achieve it by cohesively focusing on the ‘needs’ and working on regulation (regulation should focus on holistic grid needs), operations (e.g., markets and balancing authority products), and innovation (e.g., newer technologies like hydrogen).

Energy, water, and food shortages, along with irreversible environmental damage and climate changes, are bound to happen within a decade if the current course of action is maintained, preparing the “perfect storm” – a chain of interrelated events that could lead to major stress on the global system.

Energy plays a central role in the complex balance between humankind and the planet: poor strategies for the energy system will lead to disaster; but immediate, radical action can still mitigate what will otherwise be an unprecedented crisis. Reduction of the carbon intensity at the level of primary energy demand is one of the most impactful strategies. Current actions toward this goal, however, including the Nationally Determined Contributions (i.e., the climate actions pledged by the countries that ratified the Paris Agreements), are far from being adequate, and a much stronger effort is required. In this perspective, we draw inspiration from a visionary scientist of the past century, who pioneered the idea of a society powered by solar energy, and show, by a critical presentation of energy and carbon emission data, how this vision is now coming true. We focus our attention in particular to photovoltaics and analyze the factors that make it one of the key energy sources for the short and for the long term: economical convenience, the opening of very large markets, and the push by key players of the energy system.

Development of high-efficiency solar cell modules and new application fields are significant for the further development of photovoltaics (PV) and creation of new clean energy infrastructure based on PV. Especially, development of PV-powered EV applications is desirable and very important for this end. This paper shows analytical results for efficiency potential of various solar cells for choosing candidates of high-efficiency solar cell modules for automobile applications. As a result of analysis, Si tandem solar cells are thought to be some of their candidates. This paper also overviews efficiency potential and recent activities of various Si tandem solar cells such as III-V/Si, II-VI/Si, chalcopyrite/Si, perovskite/Si and nanowire/Si tandem solar cells. The III-V/Si tandem solar cells are expected to have a high potential for various applications because of high efficiency with efficiencies of more than 36% for 2-junction and 42 % for 3-junction tandem solar cells under 1-sun AM1.5 G, lightweight and low-cost potential. Recent results for our 28.2 % efficiency and Sharp’s 33% mechanically stacked InGaP/GaAs/Si 3-junction solar cell are also presented. Approaches to automobile application by using III-V/Si tandem solar cells and static low concentration are presented.

This review focuses on state-of-the-art research and development in the areas of flexible and stretchable inorganic solar cells, explains the principles behind the main technologies, highlights their key applications, and discusses future challenges.

Flexible and stretchable solar cells have gained a growing attention in the last decade due to their ever-expanding range of applications from foldable electronics and robotics to wearables, transportation, and buildings. In this review, we discuss the different absorber and substrate materials in addition to the techniques that have been developed to achieve conformal and elastic inorganic solar cells which show improved efficiencies and enhanced reliabilities compared with their organic counterparts. The reviewed absorber materials range from thin films, including a-Si, copper indium gallium selenide, cadmium telluride, SiGe/III–V, and inorganic perovskite to low-dimensional and bulk materials. The development techniques are generally based on either the transfer-printing of thin cells onto various flexible substrates (e.g., metal foils, polymers, and thin glass) with or without shape engineering, the direct deposition of thin films on flexible substrates, or the etch-based corrugation technique applied on originally rigid cells. The advantages and disadvantages of each of these approaches are analyzed in terms of achieved efficiency, thermal and mechanical reliability, flexibility/stretchability, and economical sustainability.

Partial shading of Cu(In,Ga)(Se,S)2 (CIGS) photovoltaic (PV) modules is getting more attention, as is witnessed by the increase in publications on this topic in recent years. This review will give an overview of shading tests executed on CIGS modules and focuses on the more fundamental aspects that are often studied on cells. Generally, CIGS modules display very attractive performance under predictable row-to-row shading. However, potential damage could occur under nonoptimal shading orientations: module output after shading tests could reduce due to the formation of local shunts, often called wormlike defects. The influence of many factors on the formation of these defects, including the internal currents and voltages and the shape and intensity of the shade, will be discussed. This review allows an increased insight in the degradation mechanisms caused by partial shading, which would ultimately lead to the introduction of more shade-tolerant CIGS PV products in the future.

In a bid to further reduce the cost of the front Ag contact metallization in Si solar cells, Cu is the potential alternative to replace the Ag in the Ag paste. However, this requires an understanding of the contact mechanism of screen-printable Ag/Cu paste in Si solar cell through rapid thermal process. The pastes with different weight percent of Cu (0 wt%, 25 wt% and 50 wt%) were used and the Voc of the cells was reduced with the increasing weight percent of Cu. This is because the presence of Cu in the paste changed the microstructure of the Ag/Cu/Si contact through Cu doping of the glass frits and hence increasing the Tg of the glass. The increased Tg of the glass impeded the uniform spreading of the molten glass and resulted in poor wetting and etching of the SiNx, which impacted the contact as evident in ideality factor of less than unity. This also led to the formation of agglomerated Ag crystallites with features of 700 nm in length and 200 nm in depth, which is close to the p-n junction, of which depth is ∼300 nm. However, the interface glass layer acted as an effective diffusion barrier layer to prevent Cu atoms from diffusing into the Si emitter, which is quite remarkable for Cu not to diffuse into silicon at high temperature. Further investigation of the Ag/Cu contacts with the conductive AFM in conjunction with the SEM and STEM analyses revealed that the growth of Ag crystallites in the Si emitter is responsible for carrier conduction the gridlines as with the pure Ag paste.

Using general-purpose photovoltaic device model, we have simulated the operation and functionality of a working Sn perovskite/Cu2O hole transport layer (HTL)/Cu back-contact device versus a standard Pb perovskite/Spiro HTL/Ag back-contact device. The results are extremely promising in that they showcase comparable cell efficiencies, with the Sn perovskite/Cu2O HTL/Cu back-contact device showing a highest 22.9% efficiency [Jsc of 353.4 A/m2, Voc of 0.84 V, fill factor (FF) of 0.77] at 427 nm active layer thickness compared with 24.6% of the standard Pb perovskite/Spiro HTL/Ag back-contact device (Jsc of 356.8 A/m2, Voc of 0.82 V, FF of 0.84) at the same active layer thickness. Jsc, Voc, and FF kinetics reveal that the Sn perovskite/Cu2O HTL/Cu back-contact device can perform better by reducing the recombination centers both within each layer matrix and in the interfacial contacts.

Tandem organic solar cells with two stacked cells were fabricated using semiconducting polymers and fullerene derivatives. A thin intermediate multilayer of calcium, silver, and molybdenum oxide connects the front and the back cells. Bulk heterojunction (BHJ) films of the low band gap (BG) polymer, poly[N-9″-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT), and [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) are used for the front cell. As for the back cell of the tandem structure, the same PCDTBT:PC71BM BHJ (T1) or the high BG polymer poly(3-hexylthiophene) (P3HT) blended with [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) BHJ (T2) are used. The critical role of interlayer properties on the photovoltaic performance of devices are investigated. The observed open-circuit potential for the tandem cell approaches the sum of the potentials of the two respective subcells, demonstrating the potential for increasing the voltage of the solar cell using the tandem structure even with same or lower band gap polymer in the front.

In this work, graphene and graphene oxide were synthesized by the modified Hummers method. In order to use graphene in dye-sensitized solar cell (DSSC), TiO2–graphene was prepared by a simple chemical method and used in the DSSC photoanode at different concentrations of graphene to investigate DSSC performance. Utilizing the FE-SEM images, it was observed that accumulation of TiO2 nanoparticles disappeared and a different distribution of nanoparticles was formed on the graphene sheet. Moreover, the UV-vis spectra showed that TiO2–graphene nanocomposites can absorb a wide range of light in comparison with pure TiO2. Structural characterization of TiO2–graphene nanocomposites is confirmed by the FT-IR and Raman analysis. The results have shown that in the presence of graphene, the DSSC performance significantly improved by reducing the recombination. In addition, it has been shown that excess graphene concentration is not proper for DSSC performance. The best result for TiO2–graphene nanocomposite was obtained when the concentration of 1.5% graphene was applied.

Two wide band gap conjugated polymers, namely PBDT-TT25 and PBDT-TT36, derived from (4,8-bis(4,5-dioctyl-thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)bis(trimethylstannane) with 2,5-dibromothieno[3,2-b]thiophene (TT25) or 3,6-dibromothieno[3,2-b]thiophene (TT36), have been synthesized by simply altering the linker positions of thieno[3,2-b]thiophene unit. The impact of linker positions on the energy levels, aggregation, active layer morphology, and optical and photovoltaic properties was evaluated systemically. We found that the absorption was greatly broadened, and the highest occupied molecular orbital (HOMO) energy level was elevated as the result of the significantly reduced twist angle on the polymer backbone when the linker positions changed from 3,6-isomer to 2,5-isomer. Therefore, the optimal inverted polymer solar cells exhibited a 1.87 times enhancement in power conversion efficiencies (PCE), which was mainly ascribed to the higher short circuit current densities (JSC) and fill factor (FF) of the devices mainly benefited from the widened, stronger absorption, higher hole mobility, and more ordered structure.