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Wide bandgap perovskites are being widely studied in view of their potential applications in tandem devices and other semitransparent photovoltaics. Vacuum deposition of perovskite thin films is advantageous as it allows the fabrication of multilayer devices, fine control over thickness and purity, and it can be upscaled to meet production needs. However, the vacuum processing of multicomponent perovskites (typically used to achieve wide bandgaps) is not straightforward, because one needs to simultaneously control several thermal sources during the deposition. Here a simplified dual‐source vacuum deposition method to obtain wide bandgap perovskite films is shown. The solar cells obtained with these materials have similar or even larger efficiency as those including multiple A‐cations, but are much more thermally stable, up to 3500 h at 85 °C for a perovskite with a bandgap of 1.64 eV. With optimized thickness, record efficiency of >19% and semitransparent devices with stabilized power output in excess of 17% are achieved. [ABSTRACT FROM AUTHOR]

Improving the performance of solar modules requires the implementation of both spectral and directional irradiance optimization. The performance of bifacial four-terminal tandem minimodules with a 100 cm2 area is reported, both indoor and outdoor measurements. We demonstrate a 24.5 mW/cm2 (bifacial irradiance 200 W/m2) bifacial tandem power density, measured according to a tandem adapted IEC60904-1-2 protocol, which constitutes a 3 mW/cm2 gain with respect to monofacial use. In addition, we show that in outdoor measurements bifacial four terminal tandems outperform identical monofacial four terminal tandems by 26% on average, depending on incident angle, injection level and temperature, in a 10% albedo environment. The average gain is higher for outdoor performance than for indoor performance, due to variations in relative rear irradiance. [ABSTRACT FROM AUTHOR]

Sputtered transparent conducting oxides (TCOs) are widely accepted transparent electrodes for several types of high‐efficiency solar cells. However, the different sputtering yield of atoms makes stoichiometric transfer of target material challenging for multi‐compounds. Additionally, the high kinetic energies of the arriving species may damage sensitive functional layers beneath. Conversely, pulsed laser deposition (PLD) is operated at higher deposition pressures promoting thermalization of particles. This leads to stoichiometric transfer and additionally reduces the kinetic energy of ablated species. Despite these advantages, PLD is rarely used within the photovoltaic community due to concerns about low deposition rates and the scalability of the technique. In this study, wafer‐scale (4‐inch) PLD of high‐mobility Zr‐doped In2O3 (IZrO) TCO for solar cells is demonstrated. IZrO films are grown at room temperature with deposition rate on par with RF‐sputtering (>4 nm min−1). As‐deposited IZrO films are mostly amorphous and exhibit excellent optoelectronic properties after solid phase crystallization at <200 °C. 100‐nm thick films feature a sheet resistance of 21 Ω◻−1 with electron mobilities ≈70 cm2 V−1s−1. PLD‐grown IZrO is applied as rear electrode in efficient semi‐transparent halide perovskite solar cells leading to the improved stabilized maximum power point efficiency (15.1%) as compared to the cells with sputtered ITO electrodes (11.9%). [ABSTRACT FROM AUTHOR]

Abstract The perovskite/c-Si tandem technology is considered as a cost-effective approach to realize a cell efficiency beyond the limit of single-junction (SJ) c-Si cells. Compared to its counterpart of 2-terminal (2T) configuration, 4-terminal (4T) tandem has the advantages such as no constraint of current matching and potentially simple mechanical stacking. But one of the largest challenges is the limited near-infrared (NIR) transmission of the semi-transparent perovskite solar cell (ST-PSC), which has been a bottleneck to the c-Si bottom cell performance and eventually the whole tandem cell performance. The highest NIR transmittance that has been reported is about 84%. In this contribution, we demonstrate a p-i-n planar ST-PSC with an efficiency as high as 15.7% and with a record NIR transmittance of about 92%. It is realized by optimization of the tin-doped indium oxide (ITO) material properties and light management. This NIR-transparent and high-efficiency ST-PSC leads to a 4T tandem cell efficiency of 25.7%, using an interdigitated-back-contact (IBC) c-Si bottom cell. Highlights • Record near-infrared transmittance of 92% for semi-transparent perovskite solar cells. • Detailed optical loss analysis carried out with validated optical models and input parameters. • 4-terminal perovskite/c-Si cell efficiency of 25.7%. [ABSTRACT FROM AUTHOR]

Scalable sheet-to-sheet slot die coating processes have been demonstrated for perovskite solar cells and modules. The processes have been developed on 6 in. × 6 in. glass/ITO substrates for two functional layers: the perovskite photo-active layer and the Spiro-OMeTAD hole transport layer. Perovskite solar cells produced using these slot die coating processes demonstrate device performances identical to the spin coated devices. All manufactured devices illustrate a high level of reproducibility. The developed slot die coating processes were also used for the manufacturing of perovskite PV modules. Large area modules of 12.5 × 13.5 cm 2 were realized by slot die coating on 6 in. × 6 in. substrates in combination with newly developed laser ablation processes for conventional P1-P2-P3 monolithic cell interconnections. The modules demonstrate power conversion efficiencies above 10%, with a power output of 1.7 W. This achievement is an important milestone in the development of up-scalable manufacturing technologies for perovskite PV modules. [ABSTRACT FROM AUTHOR]

Indium-tin-oxide-free (ITO-free) polymer solar cells with composite electrodes containing current-collecting grids and a semitransparent poly(3,4-ethylenedioxythiophene):polystyrenesulfonate) (PEDOT:PSS) conductor are demonstrated. The up-scaling of the length of the solar cell from 1 to 6 cm and the effect of the grid line resistance are explored for a series of devices. Laser-beam-induced current (LBIC) mapping is used for quality control of the devices. A theoretical modeling study is presented that enables the identification of the most rational cell dimension for the grids with different resistances. The performance of ITO-free organic solar cells with different dimensions and different electrode resistances are evaluated for different light intensities. The current generation and electric potential distribution are found to not be uniformly distributed in large-area devices at simulated 1 Sun illumination. The generated current uniformity increases with decreasing light intensities. [ABSTRACT FROM AUTHOR]

Abstract: ITO-free organic solar cells with ink-jet printed current collecting grids and high conducting PEDOT:PSS as a composite anode are demonstrated. Inkjet printed current collecting grids with different cross-sectional areas have been investigated. The effect of the width and height of the grid lines and busbars has been measured and modeled by direct current (DC) simulations. The electrical potential in devices with different grid profiles have been calculated and reveal critical bottlenecks in the grid electrode geometry, as the ability of the busbar to collect all the current. Experimentally, the upper limit of the conductivity of the ink-jet printed current collecting grids is limited by the topology of the grids and shadow losses in the solar cells. [Copyright &y& Elsevier]

Abstract: A new encapsulation method for organic solar cells has been tested on flexible solar modules and cells embedded in polyurethane, sandwiched between a tempered glass plate and a polycarbonate plate. Panels, each containing 10 organic solar modules/cells, were fabricated and installed for outdoor exposure in eight different countries for 4½ months. In order to minimize potential deviations in procedures and equipment, one person was responsible for the fabrication, installation and initial and final IV-measurements of the panels using the same equipment for all measurements and calibrations. The encapsulated modules/cells showed significantly reduced degradation compared with previous studies, with final average efficiencies around 40% of the original after 4½ months outdoor exposure. Photodegradation was furthermore found not to be the primary source of degradation. [Copyright &y& Elsevier]

Indium-tin-oxide (ITO) free polymer solar cells prepared by ink jet printing a composite front electrode comprising silver grid lines and a semitransparent PEDOT:PSS conductor are demonstrated. The effect of grid line density is explored for a large series of devices and a careful modeling study enabling the identification of the most rational grid structure is presented. Both optical and light beam induced current (LBIC) mapping of the devices are used to support the power loss model and to follow the evolution of the performance over time. Current generation is found to be evenly distributed over the active area initially progressing to a larger graduation in areas with different performance. Over time coating defects also become much more apparent in the LBIC images. [ABSTRACT FROM AUTHOR]

Abstract: The presence of a transparent conductive electrode such as indium tin oxide (ITO) limits the reliability and cost price of organic photovoltaic devices as it is brittle and expensive. Moreover, the relative high sheet resistance of an ITO electrode on flexible substrates limits the maximum width of a single cell. We have developed an alternative ITO-free transparent anode, based on solution processed high conductive PEDOT:PSS in combination with a printed current collecting grid. The screen printed silver grid demonstrates a typical sheet resistance of 1Ω/□ with 6.4–8% surface coverage. The efficiency of a flexible device with an active area of 4cm2 with such a grid is much higher than a similar device based on ITO. Furthermore, as this composite anode is solution-processed, it is a step forward towards low-cost large area processing. [Copyright &y& Elsevier]

Abstract: In order to reach the objective of low-cost, large area organic photovoltaic systems, we build up a knowledge base concerning the influence of process conditions on the performance of polymer solar cells. A large area solar cell module, with roll-to-roll coated PEDOT:PSS and photoactive layers (based on P3HT:[C60]PCBM blend) on a flexible substrate, has been demonstrated. Both the PEDOT:PSS and photoactive layer were deposited by slot die coating. A non-chlorinated solvent was used for the deposition of the photoactive blend. The flexible solar cell module illustrated a power conversion efficiency of 0.7% under AM 1.5 conditions. Methods to further improve the technological process are proposed. [Copyright &y& Elsevier]

The electro-optical properties of thin films of electron donor-acceptor blends of a fluorene copolymer (PF10TBT) and a fullerene derivative (PCBM) were studied. Transmission electron microscopy shows that in these films nanocrystalline PCBM clusters are formed at high PCBM content. For all concentrations, a charge transfer (CT) transition is observed with absorption spectroscopy, photoluminescence, and electroluminescence. The CT emission is used as a probe to investigate the dissociation of CT excited states at the donor-acceptor interface in photovoltaic devices, as a function of an applied external electric field and PCBM concentration. We find that the maximum of the CT emission shifts to lower energy and decreases in intensity with higher PCBM content. We explain the red shift of the emission and the lowering of the open-circuit voltage (VOC) of photovoltaic devices prepared from these blends with the higher relative permittivity of PCBM (εr = 4.0) compared to that of the polymer (εr = 3.4), stabilizing the energy (ECT) of CT states and of the free charge carriers in blends with higher PCBM concentration. We show that the CT state has a short decay time (τ = ca. 4 ns) that is reduced by the application of an external electric field or with increasing PCBM content. The field-induced quenching can be explained quantitatively with the Onsager-Braun model for the dissociation of the CT states when including a high electron mobility in nanocrystalline PCBM clusters. Furthermore, photoinduced absorption spectroscopy shows that increasing the PCBM concentration reduces the yield of neutral triplet excitons forming via electron-hole recombination, and increases the lifetime of radical cations. The presence of nanocrystalline domains with high local carrier mobility of at least one of the two components in an organic heterojunction may explain efficient dissociation of CT states into free charge carriers. [ABSTRACT FROM AUTHOR]

A two-step sequential deposition method has been applied to prepare the solar cells with two types of perovskites Cs 0.15 FA 0.85 Pb(I 0.95 Cl 0.05) 3 and Cs 0.15 FA 0.85 Pb(I 0.95 Br 0.05) 3. In order to obtain the perovskite layers, the different sources of bromine and chlorine atoms were used for synthesis. The performance and time stability of chloride-based photocells are worse in comparison to the bromide-based devices. It can be explained by the effect of an accumulation of Cl atoms at the interfaces between the chloride-based perovskites and the layer of PCBM. Such a process causes an increasing of interface recombination. Also, the bulk density of states and, consequently, the bulk recombination of charge carriers seem to be higher for the perovskite layers obtained with chlorine atoms. The two-step technique applied to create the bromide perovskites less influences the photocells performance as in the case of one-step deposition. We can explain this observation by an existence of nucleation sites in the inorganic layer which improve the growth of a perovskite material. [Display omitted] • The sequential deposition method was applied to prepare perovskite solar cells. • The dual cation (2C) perovskites were investigated. • Different sources of Br and Cl atoms were used for synthesis of perovskites. [ABSTRACT FROM AUTHOR]

An organic bulk heterojunction photovoltaic device based on a blend of two conjugated polymers, a polyphenylenevinylene as the electron donor and a red emitting polyfluorene as the acceptor, is presented with a maximum external quantum efficiency of 52% at 530 nm and a power conversion efficiency, measured under AM1.5G, 100 mW/cm2 conditions, of 1.5% on an active area of 0.36 cm2. [ABSTRACT FROM AUTHOR]

We report a cooperative study conducted between different laboratories to investigate organic solar cell degradation with respect to P3HT material properties and different solar cell architectures. Various batches of P3HT were collected from different suppliers reflecting commercial availability as well as properties variability. Among the materials properties explicitly considered were the molar mass, dispersity, regio-regularity, impurities by trace metals and intrinsic doping evaluated from radical concentrations. Each of the participating laboratories contributing test devices applied their own layer stack, i.e. their own device architecture and layout. This variation was appreciated as another parameter for evaluation. Even though a large amount of devices failed due to extrinsic degradation effects, indeed, some materials properties were found to be more important than others for obtaining long lifetimes and high stability of P3HT-based polymer solar cells. • P3HT:PCBM solar cells made from commercially available P3HTs were aged under three different ISOS protocols. • Solar cells were built by five different labs resulting in 5 different architectures. • The P3HT batches were studied for their properties like impurities, molar mass, dispersity, etc. • All P3HTs performed similar in regard to stability we concluded that commercially available P3HTs offer viable properties. • Layer stack and processor experience with P3HT used had a larger impact on stability than polymer properties. [ABSTRACT FROM AUTHOR]