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The color-tuning strategies of solid-state light-emitting devices (ss-LEDs) are mainly focused on engineering molecular structures. In this paper, for the first time, we developed a facile strategy for tuning the electroluminescence (EL) color from orange to green through the addition of the ionic additive TBAP (tetrabutylammonium perchlorate). To achieve the active ionic emissive compound for use in a light-emitting electrochemical cell (LEC), the neutral biscyclometalated bromo tetrazole iridium(III) [Ir(ppy)2(BrTz)] was exchanged to its cationic complex, [Ir(ppy)2(BrTz-Me)]ClO4 (ppy = 2-phenyl pyridine, BrTz = 4-bromo-2-pyridine tetrazole, BrTz-Me = 4-bromo-2pyridine methyl tetrazole) with a new synthetic strategy. This method allows employing neutral Ir-cyclometalated complexes, which are ruled out for use in LECs because of their non-ionic behaviors. In the following, an LEC based on the new cationic [Ir(ppy)2(BrTz-Me)]ClO4 as the emissive layer was fabricated between the FTO (fluorine-doped tin oxide) anode and Ga:In alloy cathode without using any additive or polymers, which makes this configuration the simplest ss-LED so far. By adding the ionic additives, the electroluminescence characteristics of [Ir(ppy)2(BrTz-Me)]ClO4 were dramatically increased, including luminance (L) from 162.8 cd/m2 for the device with an additive to 212.9 and 355.9 cd/m2 for devices containing LiTFSI (bis(trifluoromethane)sulfonamide lithium salt) and TBAP, respectively. In particular, when TBAP was added to the [Ir(ppy)2(BrTz-Me)]ClO4 complex, the irradiance was significantly increased from 166.4 to 220.8 mu W/cm2 with an efficacy of 1.78 cd/A and external quantum efficiency (EQE) value of 2.14%. The obtained EL results clearly showed that adding TBAP and LiTFSI significantly improved the electroluminescence characteristics and tuned the electroluminescence color.

The commercialization of perovskite solar cells (PSCs) has seen an important limitation in the instability that afflicts the hole-transporting layer (HTL), namely, spiro-OMeTAD, used in high-effici...

Halide perovskite solar cells designed using planar architectures are rapidly becoming of high interest due to their low-temperature fabrication process. As the Electron Selective Layer, SnO2 can enhance charge transfer from perovskite to electron transport layers leading to the reduction of charge accumulation at the interface exploiting the larger band offset with perovskite and a higher electron mobility compared with traditional TiO2. Herein, we developed a method for the fabrication of low-temperature planar PSCs under ambient conditions. The scalable Crystal Engineering approach was successfully applied to fabricate the CH3NH3PbI3 absorbing layer on low-temperature planar SnO2 under atmospheric conditions (fully out of glove-box). Photovoltaic characterization showed high-reproducible hysteresis-free planar perovskite solar cells with a maximum power conversion efficiency of 17.6%. The photophysical properties of the PSCs, evaluated by transient photovoltage and photocurrent analysis, showed the excellent capability of SnO2 to extract charge for perovskite. Non-encapsulated n-i-p planar solar cells indicated promising stability under atmospheric conditions, maintaining 90% of the initial efficiency for more than 1000 h. We demonstrate that the scalable air insensitive crystal engineering method is a promising approach for industrialization and fabrication of high efficiency, air-stable, and low-temperature planar perovskite solar cells with high reproducibility fabrication.

The halide perovskite photovoltaic technology can be scaled to large area modules and panels using printing processes and laser patterning. Here, we will present the progresses made to scale up from small area solar cells to modules and panels up to a dimension of 0.5 sqm. By working in controlled atmosphere (Glove Box with nitrogen) and apply conventional spin-coating technique it Is possible to easily scale up from 9 to 140 cm2 active area with efficiencies above 20% for the smallest modules and 14.7% for the largest. Specific efforts have been devoted to developing a deposition process out of the glove box (GB) in conventional ambient air. We transfer out of the GB several coating technologies, including blade coating and slot-die. To do this without penalizing efficiency and stability, a specific formulation of perovskite absorber and doping strategies of transporting layer have been formulated together with specific quencing techniques based on air, vacuum and solvents. These optimizations permitted to realized perovskite solar modules with an efficiency of > 17% on an active area of 43 cm2, keeping above 90% of the initial efficiency after 800 h thermal stress at 85 ��C. One of the critical issues scaling the cell to module size is the control of interface properties. We demonstrated that tuning of interface properties can be successfully obtained by applying two-dimensional (2D) materials, such as graphene, functionalized MoS2, MXenes as well as 2D Perovskite. This permitted also to increase the stability of the cell (T80) well beyond 1000h under light soaking and thermal stress tests.https://www.nanoge.org/proceedings/NSM22/61ae458bb25d6d736516cdac

Solar cells (SCs) are the most ubiquitous and reliable energy generation systems for aerospace applications. Nowadays, III–V multijunction solar cells (MJSCs) represent the standard commercial technology for powering space-craft, thanks to their high-power conversion efficiency and certified reliability/stability while operating in orbit. Nevertheless, spacecraft companies are still using cheaper Si-based SCs to amortize the launching costs of satellites. Moreover, in recent years, new SCs technologies based on Cu(In,Ga)Se2(CIGS) and perovskite solar cells (PSCs) have emerged as promising candi-dates for aerospace power systems, because of their appealing properties such as lightweightness, flexibility, cost-effective manufacturing, and excep-tional radiation resistance. In this review the current advancements and future challenges of SCs for aerospace applications are critically discussed. In particular, for each type of SC, a description of the device’s architecture, a summary of its performance, and a quantitative assessment of the radia-tion resistance are presented. Finally, considering the high potential that 2D-materials (such as graphene, transition metal dichalcogenides, and transition metal carbides, nitrides, and carbonitrides) have in improving both performance and stability of SCs, a brief overview of some important results concerning the influence of radiation on both 2D materials-based devices and monolayer of 2D materials is also included.

The photoluminescence (PL) intensity is often used as an indicator of the performance of perovskite solar cells and indeed the PL technique is often used for the characterization of these devices and their constituent materials. Herein, a systematic approach is presented to the comparison of the conversion efficiency and the PL intensity of a cell in both open-circuit (OC) and short-circuit (SC) conditions and its application to multiple heterogeneous devices. It is shown that the quenching of the PL observed in SC conditions is a good parameter to assess the device efficiency. The authors explain the dependence of the PL quenching ratio between OC and SC on the cell efficiency with a simple model that is also able to estimate the carrier extraction time of a device.

The perovskite solar era has demonstrated 25.5% efficiency in only 10 years of research, reaching the performance levels of other photovoltaics technologies such as Si and GaAs, showing potentially low-cost manufacturing and process versatility. However, these results are achieved only on small area cells, with an active area equal or lower to 0.1 cm(2). The upscaling development of perovskite solar technology requires the use of additional processes to reduce losses encountered for large areas; for this reason, laser processing becomes necessary to design connected cells into modules. In this work, cell-to-module losses in perovskite solar modules are reduced by optimizing the laser design, establishing a relationship between geometrical fill factor, cell area width, and P1-P2-P3 laser parameters. Upscaling the process from 2.5 x 2.5 to 10 x 10 cm(2) an efficiency of 18.71% and 17.79% is achieved on active area of 2.25 and 48 cm(2) respectively, with only 5% relative losses when scaling from to minimodule to module size. A minipanel is fabricated on 20 x 20 cm(2), showing 11.9% stabilized efficiency and 2.3 W on an active area of 192 cm(2), among the highest reported in literature so far at this size.

Cost management and toxic waste generation are two key issues that must be addressed before the commercialization of perovskite optoelectronic devices. We report a groundbreaking strategy for eco-friendly and cost-effective fabrication of highly efficient perovskite solar cells. This strategy involves the usage of a high volatility co-solvent, which dilutes perovskite precursors to a lower concentration (1.4 M) solution. More than 70% of toxic waste and material cost can be reduced. Mechanistic insights reveal ultra-rapid evaporation of the co-solvent together with beneficial alteration of the precursor colloidal chemistry upon dilution with co-solvent, which in-situ studies and theoretical simulations confirm. The co-solvent tuned precursor colloidal properties also contribute to the enhancement of the stability of precursor solution, which extends its processing window thus minimizing the waste. This strategy is universally successful across different perovskite compositions, and scales from small devices to large-scale modules using industrial spin-coating, potentially easing the lab-to-fab translation of perovskite technologies., A universal strategy is reported for formation of very low concentration of perovskite precursor inks that yields high-efficiency photovoltaics while substantially reducing toxic waste generation, fabrication cost and process complexity, thus taking a step closer towards commercialization.

Flexible perovskite solar cells (f-PSCs) are light-weight, conformal and thus ideal for seamless integration of photovoltaics onto wearable and portable electronics. Nevertheless, the spread of f-PSCs is limited by both the lower efficiency compared to rigid counterparts and the employment of costly materials. Among them, hole-transporting materials (HTM) represent the most expensive component and also a weak spot for long-term stability, due to poor resistance against heat and moisture. Here, we propose poly-3-hexylthiophene (P3HT)-modified HTMs embodying benzothiadiazole (BTD) moieties as electron-poor host. BTD is inserted along P3HT backbone, creating a donor-acceptor system able to promote the charge mobility throughout the HTM. A first series of copolymers, synthetized by Stille coupling, shows a decrease of benzothiadiazole/thiophene ratio (1:2, 1:4, 1:6), allowing to modulate both electronic and optical properties. Additionally, a greener approach (Kumada polycondensation) is employed to synthetize a homologous copolymer (VI-LM-027) embodying a lower amount of BTD that, used as HTM in f-PSCs, leads to power conversion efficiency comparable to commercially available P3HT and shows improved stability under continuous illumination. Finally, VI-LM-027 is also employed in 6 × 6 cm2 modules, delivering 6.9% efficiency on 16 cm2 of active area and demonstrating the feasibility of the proposed HTMs for large area manufacture.

Flexible perovskite solar cells (f-PSCs) are light-weight, conformal and thus ideal for seamless integration of photovoltaics onto wearable and portable electronics. Nevertheless, the spread of f-PSCs is limited by both the lower efficiency compared to the conventional rigid counterparts and the employment of costly materials. Among them, hole-transporting materials (HTM) represent the most expensive component and also a weak spot for long-term stability, due to poor resistance against heat and moisture. In this context, we propose poly-3-hexylthiophene (P3HT)-derivated HTMs embodying benzothiadiazole (BDT) moieties as electron-poor host. BDT is inserted along P3HT polymeric backbone, creating a donor-acceptor system able to promote the charge mobility throughout the HTM. A first series of copolymers, synthetized by Stille coupling, shows an increase of benzothiadiazole/thiophene ratio (namely, 1:2, 1:4, 1:6), allowing to modulate both their electronic and optical properties. Additionally, a greener approach (Kumada polycondensation) is employed to synthetize a homologous copolymer (VI-LM-027) that, used as HTM in f-PSCs, leads to power conversion efficiency comparable to commercially available P3HT and shows improved stability under continuous illumination. Finally, VI-LM-027 is also employed in 6x6 cm2 modules, delivering 6.9% efficiency on 16 cm2 of active area and demonstrating the feasibility of the proposed HTMs for large area manufacture.

In the search for improvements in perovskite solar cells (PSCs), several different aspects are currently being addressed, including an increase in the stability and a reduction in the hysteresis. Both are mainly achieved by improving the cell structure, employing new materials or novel cell arrangements. We introduce a hysteresis-free low-temperature planar PSC, composed of a poly(3-hexylthiophene) (P3HT)/CuSCN bilayer as a hole transport layer (HTL) and a mixed cation perovskite absorber. Proper adjustment of the precursor concentration and thickness of the HTL led to a homogeneous and dense HTL on the perovskite layer. This strategy not only eliminated the hysteresis of the photocurrent, but also permitted power conversion efficiencies exceeding 15.3%. The P3HT/CuSCN bilayer strategy markedly improved the life span and stability of the non-encapsulated PSCs under atmospheric conditions and accelerated thermal stress. The device retained more than 80% of its initial efficiency after 100 h (60% after 500 h) of continuous thermal stress under ambient conditions. The performance and durability of the PSCs employing a polymer/inorganic bilayer as the HTL are improved mainly due to restraining perovskite ions, metals, and halides migration, emphasizing the pivotal role that can be played by the interface in the perovskite-additive hole transport materials (HTM) stack.

The PTAA polymer (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]) is often used as a hole transport material (HTM) for high-efficiency perovskite solar cells (PSCs). However, there are great differences within the solar cell efficiencies reported. Herein, we show that when increasing PTAA molecular weight (MW) from 10 to 115 kDa, the power conversion efficiency also increases. We analyze how the differences in MW influence the interfacial carrier losses in the PSCs under operando conditions using advanced photoinduced spectroscopic techniques. Moreover, we compare kinetics and structural/morphological effects by studying different PTAA MW films. Our results show that the observed differences within the reported PSC efficiencies are due to the differences in carrier recombination kinetics, which are influenced by the differences in the polymer MW.

The performance of perovskite solar cells is under direct control of the perovskite film quality and controlling the crystalinity and orientation of solution-processed perovskite film is a fundamental challenge. In this study, we present a scalable fabrication process for heteroepitaxial growth of mixed-cation hybrid perovskites (FA(1-x-y)MA(x)Cs(y))Pb(I1-xBrx)(3) in ambient atmospheric condition by using a Crystal Engineering (CE) approach. Smooth and mesoporous thin film of pure crystalline intermediate phase of PbX2 center dot 2DMSO is formed by deposition of supersaturated lead/cesium halides solution. Kinetically fast perovskite nucleation is achieved by rapid intercalation of formamidinium iodide (FAI) and methylammonium bromide (MABr) into the intermediate layer trough solvent assisted S(N)1 ligand exchange. Finally, heteroepitaxially perovskite growth is accomplished via Volmer-Weber crystal growth mechanism. All the layers are deposited under atmospheric condition (relative humidity (RH) 50-75%) with high reproducibility for various device and module dimensions. In particular, perovskite solar modules (Pmax similar to 550 mW) are successfully fabricated by blade coating under atmospheric condition. The CE approach remarkably improves the device performance by reaching a power conversion efficiency of 18.4% for small area (0.1 cm(2)), 16.5% on larger area (1 cm(2)) devices, and 12.7% and 11.6% for blade-coated modules with an active area of 17 and 50 cm(2), respectively. Non-encapsulated triple cation solar cells and modules show promising stability under atmospheric shelf life and light soaking conditions.

In less than a decade, the extensive studies performed on halide perovskite solar cells (PSCs) permitted to reach a power conversion efficiency (PCE) exceeding 24%. The studies performed on lab-scale PSCs has revealed that PCE, hysteresis, and stability are widely dependent on the quality of perovskite crystals, including crystallinity, morphology, and surfaces/interfaces characteristics. Such ample knowledge and experience has laid a solid foundation for further exploration and development of large-scale fabrication toward perovskite modules and panels. This chapter will first summarize the unique properties of halide perovskite such as crystal structure, energy band properties, charge transport, recombination, and ferroelectric properties. A detailed discussion is devoted to perovskite crystallization (from liquid phase) that involves a classical nucleation/growth mechanism. The crystal growth includes three stages: solution supersaturation, nucleation, and subsequent growth toward a large crystal, which, depending on the deposition method, could also pass through stable or metastable intermediate phases. Different deposition methods will be presented including one-step techniques based on solvent/vacuum/gas quenching and two-step deposition based on crystal engineering approach or vapor-assisted process. Single-junction and multijunction PSCs are discussed in a specific section, and the different device architectures are presented. The development of tandem solar cells, such as perovskite/silicon, attracts the interest of the scientific community being an effective approach to overcome the Shockey–Queisser limit formulated for an ideal single cell with 1.34 eV band gap achieving a maximum PCE of 33.7%. Beside the efficiency, stability is one of the key challenges for industrial exploitation of PSCs. Degradation mechanisms depending on materials, bias conditions, light soaking, and temperature are also discussed in the chapter. The last section of the chapter is devoted to large area fabrication of perovskite modules. We will discuss the optimization of interconnections between adjacent cells by using a fully laser process. The P1–P2–P3 laser ablations are used to this end and to reduce inactive regions of the modules

The conversion of solar energy into electricity via the photovoltaic (PV) effect has been rapidly developing in the last decades due to its potential for transition from fossil fuels to renewable energy based economies. In particular, the advances in PV technology and on the economy of scale permitted to reduce the cost of the energy produced with solar cells down to the energy cost of conventional fossil fuel. Thus, PV will play an important role to address the biggest challenges of our planet including global warming, climate change and air pollution. In this paper, we will introduce the photovoltaic technology recalling the working principle of the photovoltaic conversion and describing the different PV available on the market and under development. In the last section, we will focus more on the emerging technology of the halide perovskite, which is the research subject of the authors.

Perovskite solar cells (PSCs) are a type of emerging thin-film photovoltaics, which show a promising potential to catch a major portion of the near future market. However, hazardous waste-generation and cost-management of the industrial production are two key issues which need to be addressed in the commercialization process. Herein, a universal coating strategy is introduced by combination of blade and spin coating to realize a zero-waste-generation of the perovskite precursor materials for layer-by-layer deposition of 3D/2D perovskite films on large-area substrates with high uniformity and reproducibility. This leads to eliminate 90% and 95% of the materials consumption compared to the conventional spin-coating for deposition of the 3D and 2D perovskite layers, respectively, without changing of the ink precursor. Large-area PSCs have been realized by blade-spin/blade coating approach reaching 19.55% photo-conversion efficiency (PCE) over 0.92 cm(2) masked area and >1000 h T90 thermal stability at 85 degrees C. Fabricated perovskite solar modules via blade-spin/blade deposition have been reached to 18.8% PCE over 10 cm(2) active-area. The economic analysis shows the potential for >90% decrease of the operational expenditure via break-down of the material costs from 1.99 euro m(-2) in spin coating method to 0.18 euro m(-2) in blade-spin/blade coating approach.

In this work, we successfully used a pure layer of [SiW11O39]8- polyoxomethalate (POM) structure as a thin film scaffold layer of CH3NH3PbI3 based perovskite solar cells (PSCs). A smooth nanoporous surface of POM cause to amazing improvement of the photocurrent density, External Quantum Efficiency (EQE) and overall efficiency of the PSCs compare to mp-TiO2 as scaffold layer. Average PCE values of 15.5% with champion device as 16.3% could achieve by using POM and sequential deposition method of perovskite layer. Furthermore, modified and defect-free POM/perovskite interface led to elimination of the anomalous hysteresis in the current-voltage curves. Open-circuit voltage decay study show promising decrease of the electron recombination in the POM based PSCs which also related to modification of POM/perovskite interface and higher electron transport inside the POM layer.

Here, we investigated the effect of the molecular weight (MW) of poly 3-hexylthiophene (P3HT) hole-transport material on the performance of perovskite solar cells (PSCs). We found that by increasing the MW the photovoltaic performances of the cells are enhanced leading to an improvement of the overall efficiency. P3HT-based PSCs with a MW of 124 kDa can achieve an overall average efficiency of 16.2 %, double with respect to the ones with a MW of 44 kDa. Opposite to spiro-OMeTAD-based PSCs, the photovoltaic parameters of the P3HT-based devices are enhanced by increasing the mesoporous TiO2 layer thickness from 250 to 500 nm. Moreover, for a titania scaffold layer thickness of 500 nm, the efficiency of P3HT-based PSCs with high MW is larger than the spiro-OMeTAD based PSCs with the same scaffold layer thickness. Recombination reactions of the devices were also investigated by voltage decay and electrochemical impedance spectroscopy. We found that the relationship between P3HT MW and cell performance is related to the reduction of charge recombination and to the increase of the P3HT light absorption by increasing the MW.

As Hole Transport Layer (HTL) for perovskite solar cells (PSCs), Poly (3-Hexylthiophene) (P3HT) has been attracting a great interest due to its low-cost, thermal stability, oxygen impermeability and strong hydrophobicity. In this work, a new doping strategy has been developed for the P3HT as HTL in triple-cation/double-halide ((FA1-x-yMAxCsy)Pb(I1-xBrx)3) mesoscopic PSCs. Photovoltaic performances and stability of solar cells show remarkable enhancement using a composition of three dopants Li-TFSI, TBP and Co(III)-TFSI reaching power conversion efficiencies of 19.25% on 0.1 cm2 active area, 16.29% on 1 cm2 active area and 13.3% on a 43 cm2 active area module without using any additional absorber layer or any interlayer at the PSK/P3HT interface. The results illustrate positive effect of cobalt dopant on the band structure of perovskite/P3HT interface leading to an improved hole extraction and a decrease of trap-assisted recombination. Non-encapsulated large area devices show promising air stability through keeping more than 80% of initial efficiency after 1500 hr in atmospheric conditions (RH~60%, r.t.), while encapsulated devices show more than 500 hr at 85 °C thermal stability (>80%) and 100 hr stability against continuous light soaking (>90%). The boosted efficiency and the improved stability make P3HT a good candidate for low-cost large-scale PSCs.

As the hole transport layer (HTL) for perovskite solar cells (PSCs), poly(3-hexylthiophene) (P3HT) has been attracting great interest due to its low-cost, thermal stability, oxygen impermeability, and strong hydrophobicity. In this work, a new doping strategy is developed for P3HT as the HTL in triple-cation/double-halide ((FA1−x−yMAxCsy)Pb(I1−xBrx)3) mesoscopic PSCs. Photovoltaic performance and stability of solar cells show remarkable enhancement using a composition of three dopants Li-TFSI, TBP, and Co(III)-TFSI reaching power conversion efficiencies of 19.25% on 0.1 cm2 active area, 16.29% on 1 cm2 active area, and 13.3% on a 43 cm2 active area module without using any additional absorber layer or any interlayer at the PSK/P3HT interface. The results illustrate the positive effect of a cobalt dopant on the band structure of perovskite/P3HT interfaces leading to improved hole extraction and a decrease of trap-assisted recombination. Non-encapsulated large area devices show promising air stability through keeping more than 80% of initial efficiency after 1500 h in atmospheric conditions (relative humidity ≈ 60%, r.t.), whereas encapsulated devices show more than >500 h at 85 °C thermal stability (>80%) and 100 h stability against continuous light soaking (>90%). The boosted efficiency and the improved stability make P3HT a good candidate for low-cost large-scale PSCs.

Visible Light Communication technology has the potential to become a leading actor in the future 5G network, thanks to features such as efficient “re-use of re-sources”, native privacy security and human safeness (compared to radio-frequency applications). Among the several configurations achievable to realize a VLC link, the use of innovative photovoltaic devices as receiver, based on organic-inorganic printable semiconductors (hybrid perovskite materials), has the potential to pave the way to new scenario applications, thanks to the inherent cheaper costs of fabrication via roll-to-roll solution-based processes, possibly on flexible substrates. In this context, we have fabricated photo-detectors with three different types of perovskite, and used with a commercial cool-white LED to realize a prototype of visible light communication data link. Using a single-stage transimpedance amplifier for the perovskite photodetector, we have reached a remarkable frequency bandwidth close to ∼800 KHz.

Operational stability of perovskite solar cells (PSCs) is rapidly becoming one of the pressing bottlenecks for their upscaling and integration of such promising photovoltaic technology. Instability of the hole transport layer (HTL) has been considered as one of the potential origins of short life-time of the PSCs. In this work, by varying the molecular weight (MW) of doped poly(triarylamine)(PTAA) HTL, we improved by one order of magnitude the charge mobility inside the HTL and the charge transfer at the perovskite/HTL interface. We demonstrate that this occurs via the enhancement of polaron delocalization on the polymeric chains through the combined effect of doping strategy and MW tuning. By using high MW PTAA doped combining three different dopant, we demonstrate stable PSCs with typical power conversion efficiencies above 20%, retain more than 90% of the initial efficiency after 1080 h thermal stress at 85 °C and 87% of initial efficiency after 160 h exposure against 1 sun light soaking. By using this doping-MW strategy, we realized perovskite solar modules with an efficiency of 17% on an active area of 43 cm2, keeping above 90% of the initial efficiency after 800 h thermal stress at 85 °C. These results, obtained in ambient conditions, pave the way toward the industrialization of PSC-based photovoltaic technology.

A combined experimental and computational study to understand the nature of the hydrogen bonding in a crab-claw site of a new synthesized chromium Schiff base complex is reported. The fully optimized equilibrium structures of the Cr(III) complex in the presence and absence of chloride ion are obtained at the B3LYP functional in conjunction with LanL2DZ basis set. The crystal structure of the chromium Schiff base complex consists of [CrL 2 ] + cation, in which L is a tridentate Schiff base ligand with full name of N-(2-(2-hydroxyethylamino)ethyl)5-methoxysalicylideneimine, and a chloride anion, in the asymmetric unit. The chromium(III) cation possesses a distorted octahedral geometry, coordinated with four nitrogen and two phenoxo oxygen atoms derived from two chelate Schiff base ligands. The harmonic vibrational frequencies, infrared intensities and Raman scattering activities of the complexes are also reported. The scaled computational geometry and vibrational wavenumbers are in very good agreement with the experimental values of single crystal X-ray diffraction and FT-IR, respectively. The electronic properties calculations of the complexes are also performed at the TD-B3LYP/LanL2DZ level of theory. The spectroscopic excitation parameters obtained for frontier molecular orbitals of the complexes are reported as well. These findings are in good agreement with the experimental UV–Vis diffuse-reflectance spectroscopy. Parabolic diagrams are derived for the chloride insertion and hydrogen bonding in the crab-claw site with the average optimized H⋯H distances of the effective hydrogen atoms in the crab-claw site as reaction coordinate.

Here, we successfully used a pure layer of [SiW

Previous reports have observed a direct relationship between the polymer poly(3-hexylthiophene) molecular weight (MW) and the perovskite solar cell (PSC) efficiency. Herein, we analyse how the differences in MW and the differences in energetic disorder influence the interfacial carrier losses in the PSCs under operation conditions and explain the observed differences. This article is part of a discussion meeting issue ‘Energy materials for a low carbon future'.

A proper growth of Iodine based perovskite nanocrystals is crucial for photovoltaic applications and this process is highly affected from the scaffold used for the crystallization. In this work, ordered nanoporous alumina, realized by controlled anodizing of two different thickness layer of Al, deposited on glass and Indium Tin Oxide (ITO), was used as the scaffold layer for the growth of perovskite nanocrystals. We present CH3NH3PbI3 crystals successfully converted on such substrates, using three different dipping techniques. Scanning Electron Microscopy (SEM) characterization, optical microscope analysis and absorbance measurements of the as grown perovskite layers are reported.

A combined experimental and computational investigation conducted to understand the nature of the interactions between cobalt II/III redox mediators ([Co(bpy)3](2+/3+)) and their impact on the performance of the corresponding dye-sensitized solar cells (DSCs) is reported. The fully optimized equilibrium structures of cobalt(II/III)-tris-bipyridine complexes in the gas phase and acetonitrile solvent are obtained by the density functional B3LYP method using LanL2DZ and 6-31G(d,p) basis sets. The harmonic vibrational frequencies, infrared intensities and Raman scattering activities of the complexes are also calculated. The scaled computational vibrational wavenumbers show very good agreement with the experimental values. Calculations of the electronic properties of the complexes are also performed at the TD-B3LYP/6-31G(p,d)[LanL2DZ] level of theory. Detailed interpretations of the infrared and Raman spectra of the complexes in different phases are reported. Detailed atomic orbital coefficients of the frontier molecular orbitals and their major contributions to electronic excitations of the complexes are also reported. These results are in good agreement with the experimental electrochemical values. Marcus diagram is derived for the electron transfer reaction Co(II) + D35(+)→ Co(III) + D35 using the Co-N bond length as a reaction coordinate.

One-electron fast redox mediators like cobalt complexes are a new important class of mediator system in dye sensitized solar cells (DSCs) that have some special features such as fast regeneration reactions, low absorption in the visible light range without the occurrence of destructive reactions with the materials of the DSCs. In this research, for the first time, a new Schiff base cobalt complex has been synthesized and used as an efficient redox mediator system in dye sensitized solar cells which are fabricated using D35 organic dye as a sensitizer and mesoporous nanostructured titania as a photoanode. J–V measurements of the prepared DSC were carried out under AM1.5G irradiation and photoelectrochemical parameters like the open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), voltage decay and the overall efficiency were measured and compared to the conventional symmetric cobalt polypyridine complexes. The J–V curve results show enhancement of the open-circuit voltage in the DSC with the new Schiff base cobalt complex mediator compared with classic polypyridine cobalt complexes. Comparison between the dark currents of the investigated cells provides qualitative information about the electron recombination process. Lower dark currents were observed in DSCs with a titania blocking layer. Voltage decay measurements, the calculated electron lifetime and the effective recombination order (β) show lower average β values for the DSC with the Schiff base cobalt complex as a redox mediator.

One of the most thrilling developments in the photovoltaic field over recent years has been the use of organic–inorganic lead halide perovskite, such as CHlsubg3l/subgNHlsubg3l/subgPbIlsubg3l/subg (MAPbIlsubg3l/subg), as a promising new material for low-cost and highly efficient solar cells. Despite impressive power conversion efficiency (PCE) exceeding 22% demonstrated on lab-scale devices, the deposition procedures for large-area devices and automatized fabrication protocols still represent a challenge in order to achieve high-throughput serial manufacturing of modules and panels. In this work, we demonstrate that spray coating technique is an effective technique for producing mesoscopic small- and large-area perovskite solar cells (PSCs). In particular, we report a sprayed graphene-doped mesoporous TiOlsubg2l/subg (mTiOlsubg2l/subg) scaffold for mesoscopic PSCs. By successfully combining the spray coating technique with the insertion of graphene additive into the sprayed mTiOlsubg2l/subg scaffold, a uniform deposition and a significant enhanced electron transport/injection at the mTiOlsubg2l/subg/perovskite electrode is achieved. The use of graphene flakes into the sprayed scaffold boosts the PCE of small-area cells up to 17.5% that corresponds to an increase of more than 15% with respect to cells made without graphene flakes. For large-area (1.1 cmlsupg2l/supg) cells, a PCE up to 14.9% is achieved. Moreover, graphene doping of sprayed mTiOlsubg2l/subg layer allows for enhanced stability with respect to that devices where graphene is not present. The feasibility of PSCs fabrication by spray coating deposition of the mesoporous film on large-area 21×24 cmlsupg2l/supg provides a viable and low-cost route to scale the manufacturing of low-cost, stable and high-efficiency PSCs.