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Abstract: Nb doped TiO2 (Nb:TiO2) is a promising indium-free transparent conducting oxide. We have examined the growth of Nb:TiO2 thin films by pulsed laser deposition (PLD) on SrTiO3, LaAlO3, and fused silica. For <004> oriented anatase Nb:TiO2 films grown on SrTiO3 by PLD at 550 °C, the conductivity can be as high as 2500 S/cm. A nearly thickness independent conductivity for Nb:TiO2 demonstrates that the conductivity is a bulk property and not a substrate interface effect. In addition, Nb:TiO2 films deposited at room temperature were annealed at temperatures up to 750 °C in either vacuum or 1.3×10−3 Pa O2. For these films, conductivities as high as 3300 S/cm on SrTiO3 and 85 S/cm on LaAlO3 substrates were obtained for the highest temperature vacuum anneals, albeit with some loss in transparency. [Copyright &y& Elsevier]

Direct solution coating technique has emerged as a promising economically viable process for earth abundant chalcogenide absorber materials for photovoltaic applications. Here, direct ethanol based dip coating of earth abundant Cu 2 NiSnS 4 (CNTS) films on soda lime glass (SLG), molybdenum coated glass (Mo), and fluorine doped tin oxide coated glass (FTO) substrates is investigated. The structural and morphological properties of pre-annealed and sulfurized CNTS films coated on SLG, FTO, and Mo substrates are reported. The influence of dipping cycles on composition and optoelectronic properties of pre-annealed and sulfurized CNTS films deposited on SLG substrate is presented. Energy dispersive spectroscopy (EDS) and X-ray fluorescence (XRF) analysis reveal how changes in thickness and elemental composition affect morphology and optoelectronic properties. The obtained absorption coefficient, optical bandgap, resistivity and mobility of pre - annealed and sulfurized films are found to be 10 4 cm −1 , 1.5 eV, 0.48 Ωcm, 3.4 cm 2 /Vs and 10 4 cm −1 , 1.29 eV, 0.14 Ωcm, 11.0 cm 2 /Vs, respectively. These properties are well suited for photovoltaic applications and lead to the conclusion that the direct ethanol based dip coating can be an alternative economically viable process for the fabrication of earth abundant CNTS absorber layers for thin film solar cells. [ABSTRACT FROM AUTHOR]

• An analysis of temperature & injection dependent V oc and PL intensity is developed. • CdTe-based solar cells are grown with an assortment of windows and back contacts. • Band offset, shunt, and recombination effects are separated. • Standard J-V shunt resistances must be well below a kΩ cm2 to be meaningful. Band offsets at the back contact and front window layer in CdTe-based solar cells affect photovoltaic performance and challenge standard characterization methods. By analyzing the temperature and excitation dependence of both open circuit voltage and absolute photoluminescence intensity, we show that the effects band offsets can be separated from the effects of recombination and shunting. Solar cells were grown with MgZnO window layers and compared to cells with CdS window layers containing varying amounts of oxygen. It was demonstrated that band alignment rather than reduced recombination velocity is the reason for the success of MgZnO as a front interface contact. An assortment of thin back contact interlayers were also deposited, and a PbTe interlayer showed some promise as an Ohmic contact to the CdTe, though it appears to induce a photoconductive shunt. Finally, we show that the shunting resistance given by a standard current-voltage curve technique generally does not represent a physically meaningful quantity unless it is well below one kiloOhm square cm. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights: • A unique Zn blanket annealing process to control compensating defects in AZO thin films. • Decrease in compensating defects in AZO due to excess Zn diffusion. • As low as 8.8 Ω/sq sheet resistance and 90% visible transmittance of AZO is at par with commercial ITO. • Developed film performance as TCO in perovskite solar cells is quite good. Abstract Achievement of high conductivity by doping an oxide thin film while maintaining its high visible transparency remains a challenge in the field of materials science and technology. Here, we demonstrate a simple and novel technique to control compensating defects in Al doped ZnO (AZO) thin films involving a post-growth annealing process with Zn blanket. We also provide an in-depth understanding of the mechanism of achieving high conductivity. As low as 8.8 Ω/sq sheet resistance (resistivity 3.1 × 10−4 Ω cm) with 90% visible transmission value and wherefrom a figure of merit (FOM) value of 6.5 × 10−2 Ω−1 for a RF sputtered 350 nm AZO thin film can be achieved. Such very low sheet resistance has been attributed to a decrease in the number of compensating defects and lesser out diffusion of Zn in AZO. Application of the developed AZO film as conducting substrate has successfully been tested by fabricating perovskite solar cells on flexible Corning® Willow® Glass substrate. The present findings open up the possibility of enough high quality industrial-scale production of transparent conducting oxides (TCOs) bearing crucial significance from the perspective of transparent electrodes for solar cells. [ABSTRACT FROM AUTHOR]

We demonstrate the use of supersonic spraying for the deposition of silver nanowires (AgNWs) on a flexible polyimide (PI) substrate for the formation of transparent and conducting films (TCF) as an alternative to nonflexible ITO (indium tin oxide). The self-fused intersections of the NWs resulted in films with a low sheet resistance ( R s = 31 Ω/sq) and fairly high transmittance ( Tr = 92%) on a glass substrate. The effect of the impact speed of the supersonically sprayed AgNWs on the opto-electric properties of the flexible TCF was evaluated by varying the spray coating conditions. The fabricated films were characterized by X-ray diffraction analysis, atomic force microscopy, ultraviolet–visible spectroscopy, and scanning electron microscopy. Finally, cyclic bending tests were performed on the PI/AgNW films as well as PI/ZnO/indium tin oxide/AgNW films, and the changes in their electrical properties with bending were compared. [ABSTRACT FROM AUTHOR]

Abstract: Aerosol jet printing is a contactless deposition technique that is ideally suited to depositing features on very thin and fragile substrates such as Si wafers. It can also be used to optimize device geometries including the Al back contact of a Si wafer solar cell quickly. A printable Al ink is required for this process, and we report lines and solar cells prepared with such a material. The resistivities of the printed Al lines approach bulk after appropriate sintering. Al lines printed on Si wafers have been heated over a wide temperature range of 550 to 800°C to form low resistance contacts suitable for current extraction. Aerosol jet printed Al contacts to industrially produced 21cm2 polycrystalline Si solar cells performed on par with all screen printed contacts on similar cells. These promising results demonstrate the potential for non-contact printed Al to contribute to the fabrication of low-cost photovoltaic devices and modules. [Copyright &y& Elsevier]

Abstract: We prepared titania films by aerosol deposition (AD), in which titania powder is supersonically accelerated for deposition onto a substrate. These AD titania films exhibited hydrophilicity and photocatalysis under UV exposure. However, after surface modification by CF4 plasma-etching, the films showed higher hydrophilicity and lower photocatalytic effect. After sufficient modification, they exhibited superhydrophilicity, which was induced by the presence of fluorine. This type of surface modification is useful for promoting hydrophilicity under no UV light exposure. [Copyright &y& Elsevier]

• A technoeconomic model for roll-to-roll produced perovskite solar cells is established. • Manufacturing costs are dominated by materials costs (>93%). • Intense Pulsed Light has cost advantages over conventional annealing techniques. Perovskite solar technology can produce economically viable photovoltaic devices due to low cost of materials and scalable manufacturing. Solution phase deposition of all active layers lends itself to roll-to-roll fabrication methods which are well-established and have production rates of several hundred square meters per minute. In this techno-economic analysis, the opportunity to scale at this production throughput is considered with manufacturing rates exceeding one gigawatt per year in a single plant. Intense pulsed light is used for the post deposition process to minimize costs associated with the footprint, equipment, and operation. The analysis is limited to the operation of a roll-to-roll manufacturing facility producing a perovskite solar film that can be incorporated into photovoltaic modules. Costs associated with materials, labor, and equipment are considered along with utilities determined from the fundamental engineering calculations. The results show that at very large-scale operations of several gigawatts, the costs to produce the solar films range between $0.04 and $0.10 per watt. [ABSTRACT FROM AUTHOR]

Abstract: The influence of semiconductor layer morphology on the performance of solution-processed ZnO/Cu2O photovoltaics has been examined. ZnO films were prepared using three highly scalable, cost-effective methods: electrodeposition, zinc acetate decomposition, and diethyl zinc decomposition. To optimize device performance, it is found that a low density of nano-scale pores in the ZnO layer and large grains in the Cu2O is necessary. Through optimizing the ZnO morphology, one of the highest fill factors observed to date (up to 54%) in solution-processed ZnO/Cu2O was achieved. This value is comparable with the fill factor of the record-efficiency ZnO/Cu2O device, which was prepared with much larger energy inputs. [Copyright &y& Elsevier]

Abstract: Films of gallium-doped zinc oxide (GZO) were deposited on glass substrates by radio-frequency magnetron sputtering using a ceramic target of Ga:ZnO (4at.% Ga vs. Zn). Both the substrate temperature (T s) and the target–substrate distance (d ts) were varied and the effect on electrical, optical and structural properties of the resulting films were measured. The highest conductivity of 3200S/cm was obtained at a deposition temperature of 250°C, at a d ts of 51mm. This sample had the highest carrier concentration in this study, 9.6×1020/cm3. Optical transmittance of all films was <90% in the visible range. The grain size of the film grown at d ts =51mm was smaller than the grain size for films grown with a shorter d ts; moreover, the films with d ts =51mm exhibited the smoothest surface, with a root mean square surface roughness of 2.7nm. Changes in T s have a more pronounced effect on conductivity compared to changes in d ts; however, variations in structure do not appear to be well-correlated with conductivity for samples in the 2000–3200S/cm range. These results suggest that incorporation and activation of Ga is of key importance when attempting to obtain GZO films with conductivities greater than 2000S/cm. [ABSTRACT FROM AUTHOR]

Abstract: Thin film pi-conjugated poly(3,4ethylenedioxythiophene): poly(styrenesulphonate) (PEDOT:PSS) as a hole transport layer on indium tin oxide is a key element in some of the most efficient organic photovoltaic and light emitting devices to date. Films are typically deposited by spincoating, which is not readily scalable. In this paper we investigate the critical parameters for both inkjet and ultrasonic spray deposition of PEDOT:PSS thin films on commercial indium tin oxide as a potentially scalable approach to contact formation. Inkjet parameters investigated include drop spacing and substrate temperature. Ultrasonic spray coating parameters investigated include substrate temperature and solution flow rate. We also show that the ink viscosity has a Newtonian character, making it well suited for inkjet printing. Films were characterized via optical profilometry, sheet resistance and atomic force microscopy. Optimized inkjet printed and ultrasonic sprayed PEDOT:PSS films were then compared to spincast layers in a prototypical bulk heterojunction photovoltaic device employing a poly(3-hexylthiophene) and [6,6]-PCBM (6,6-phenylC61-butric acid-methyl ester) blend as the absorber. Practically all three approaches produced devices of comparable efficiency. Efficiencies were 3.6%, 3.5% and 3.3% for spin, spray and inkjet depositions respectively. [Copyright &y& Elsevier]

• Processing times were reduced to a few seconds using rapid thermal annealing. • Flexible perovskite solar cells were made with 14.56% PCE. • Radiative annealing, such as RTA, can protect underlying temperature-sensitive substrates through more tailored heat transfer to the perovskite layer. Adaptability, lightweight, and low cost of materials make flexible perovskite solar cells essential for the perovskite technology to breach commercial photovoltaic markets. Roll-to-roll manufacturing has great potential for high-throughput perovskite manufacturing; however, conventional annealing methods are not capable of producing flexible perovskite solar cells at scale. Conventional methods are time consuming and may compromise functionality of flexible substrates under tension. Here, we introduce a blade-coated perovskite thin film on flexible ITO-coated PET annealed via rapid thermal annealing (RTA) that reduces post-deposition processing time from ~150 s to ~14 s. Performance was not sacrificed for scalability as a perovskite solar cell was produced with a power conversion efficiency (PCE) of 14.58%. [ABSTRACT FROM AUTHOR]