Absolute Efficiency Increase Research Articles

Role of CdTe Interface Structure on CdS/CdTe Photovoltaic Device Performance.

Glancing angle deposition (GLAD) of CdTe can produce a cubic, hexagonal, or mixed phase crystal structure depending upon the oblique deposition angles (Φ) and substrate temperature. GLAD CdTe films are prepared at different Φ at room temperature (RT) and a high temperature (HT) of 250 °C and used as interlayers between the n-type hexagonal CdS window layer and the p-type cubic CdTe absorber layer to investigate the role of interfacial tailoring at the CdS/CdTe heterojunction in photovoltaic (PV) device performance. The Φ = 80° RT GLAD CdTe interlayer and CdS both have the hexagonal structure, which reduces lattice mismatch at the CdS/CdTe interface and improves electronic quality at the heterojunction for device performance optimization. The device performance of HT CdS/CdTe solar cells with Φ = 80° RT with 50 to 350 nm thick GLAD CdTe interlayers is evaluated in which a 250 nm interlayer device shows the best device performance with a 0.53 V increase in open-circuit voltage and fill-factor product and a 0.73% increase in absolute efficiency compared to the HT baseline PV device without an interlayer.

Optimal performances of a-Si:H/c-Si heterojunction silicon solar cells based on a statistical approach

Finding the optimal condition from a wide range of cell fabrication conditions and design parameters is typically a time-consuming and cumbersome task. In this study, the combination of the Taguchi approach and Grey relational analysis was employed for optimization of the conversion efficiency of hydrogenated amorphous silicon/crystalline silicon heterojunction (a-Si:H/c-Si HJ) solar cells. With the help of the Taguchi method via an orthogonal array, the reconstruction of the impact of input parameters on single performance characteristics is still ensured while reducing the number of simulations by 99.8%. The simulated results suggested that the density of interfacial defects (Dit) plays a key role in obtaining a high open-circuit voltage (Voc) and fill factor (FF), respectively. Meanwhile, the emitter thickness is the dominant factor in achieving a high short-circuit current density (Jsc). As a result, these two factors dominate the conversion efficiency. Furthermore, the overall optimal condition is also obtained by the Grey relational analysis. The simplified HJ cell configuration using this optimal condition displayed the highest conversion efficiency of 25.86%, yielding a 2.25% absolute increase in efficiency compared to the initial condition. The results highlight the effectiveness of our proposed approach in reducing the number of experiments needed for cell optimization.

Changes in ohmic shunts in Cu(In,Ga)Se2 devices during damp heat

To increase the bankability of photovoltaics (PV), a more accurate prediction of the lifetime and degradation-rate of PV modules is required. In past studies, average degradation rates for different technologies have been derived from field data. However, in Cu(In,Ga)Se2 (CIGS) based PV, localized shunts are commonly found in modules coming out of the factory. Although the impact of such localized defects on initial module performance has been studied in the past, their evolution and impact on module performance upon aging remain mostly unknown. In this paper, it is demonstrated that exposure of CIGS devices to elevated temperatures and humidity can result in the partial or complete recovery of localized ohmic shunts. This was observed for three types of shunting defects, each on a different CIGS device characterized before and after damp heat exposure. In each device, the reduction in shunting after damp heat could be observed in illuminated lock-in thermography, photoluminescence and current-voltage measurements. For two of the devices, the positive effect of shunt reduction was counteracted by other degradation mechanisms, such as increase in series resistance of TCO or back contact, while a 4% absolute efficiency increase was observed in the third device. Our data suggests that the shunting is mainly reduced due to oxidation of the materials initially forming the shunting path. The combined effects of moisture degradation and shunt reduction may limit detectability of moisture ingress in electrical performance data. These results illustrate the added value of regular visual inspection and luminescence in quality control.

Self‐Tracking Solar Concentrator with Absorption of Diffuse Sunlight

AbstractThe highest solar cell efficiencies are obtained with concentrating systems. However, these systems have two major drawbacks: solar tracking is needed and diffuse sunlight is poorly absorbed. Here, a system that overcomes both limitations is presented, by exploiting light‐induced halide segregation in mixed halide perovskite films. A monolayer of silica microspheres focuses direct sunlight in a mixed halide perovskite film below. Through light‐induced phase segregation a low bandgap region forms in the focal point. Together with funneling of excited states toward the low bandgap regions, this results in a voltage increase characteristic for concentrating systems. Diffuse sunlight is still absorbed by the high bandgap material, avoiding the loss of diffuse sunlight characteristic for conventional concentrators. The formation of low bandgap regions in the perovskite is dynamic, and can follow the position of the focus as the sun moves throughout the day, making solar tracking unnecessary. With detailed optical and electrical simulations, it is shown that this concept can lead to an increase in both voltage and current. This leads to a 6.6% absolute increase in power conversion efficiency compared to the film without microspheres. Absorption and emission measurements confirm the concentration effect, showing the promising potential for a self‐optimizing concentrating system.

Interface Engineering by Intermediate Hydrogen Plasma Treatment Using Dc-PECVD for Silicon Heterojunction Solar Cells

The high open-circuit voltage (VOC) in silicon heterojunction solar cells is attributed to the superior amorphous–crystalline silicon interface passivation. In this work, we investigated a method called intermediate hydrogen plasma treatment (I-HPT) in which the intrinsic amorphous silicon is exposed to hydrogen plasma in between the deposition using direct current (d.c.) plasma-enhanced chemical vapor deposition. This method can not only enhance the surface passivation but also find industrial application due to its ease of integration in the production line. Fourier transform infrared spectroscopy reveals that I-HPT makes the bulk of the amorphous matrix more disordered. We anticipate that the improvement in passivation comes from the diffusion of hydrogen from the bulk to the interface and shifting of the film closer to the “amorphous-to-microcrystalline” transition regime. Our optimized I-HPT method can obtain an implied VOC of 746 mV without annealing, which corresponds to a low surface recombination velocity of 3.2 cm/s. Therefore, we propose the I-HPT method as an alternative to high-temperature annealing which can reduce a fabrication step and processing time. The I-HPT films characterized by Raman spectroscopy do not show any hydrogen-induced crystallization. We have also demonstrated the proof of concept by applying I-HPT to a silicon heterojunction solar cell which shows ∼15 mV increase in VOC in the device and an absolute increase in efficiency by 0.3% as compared to a cell with no HPT.

Electrical passivation of III-V multijunction solar cells with luminescent coupling effect

Perimeter recombination is one of the causes identified for having a nonuniform luminescent coupling effect in III-V multijunction solar cells. A potential solution could be the electrical passivation of the multijunction solar cell perimeter. To test this hypothesis, electrical passivation of InGaP/GaAs/Ge 3-junction solar cells was done by the atomic layer deposition of thin Al 2 O 3 films. Perimeter passivation of a 3-junction solar cell relatively increased current collection measured at luminescent coupling and direct subcell excitation by as much as 11.4% and 29.8%, respectively. Meanwhile, the current homogeneity improved relatively by as much as 7.9% after electrical passivation. At 1-sun global standard illumination (AM 1.5G), 0.2% absolute conversion efficiency increase was achieved. Therefore, electrical passivation of fully working III-V multijunction solar cells is a non-invasive, post-treatment process that can recover losses due to surface defects caused by oxidation. • Post-treatment passivation for fully working multijunction solar cell. • Larger conversion efficiencies in multijunction solar cells with smaller active areas. • Spatial current uniformity improvement after perimeter passivation. • Reduction of shunt leakage current in a subcell made of indirect bandgap material. • Alleviate lateral resistance effects by electrical passivation.

Optical analysis of light management for finger designs in CPV systems

AbstractConcentrated photovoltaic (CPV) systems can achieve high energy conversion efficiencies due to their use of concentrating optics and highly efficient solar cells; however, power losses arising from the front surface reflection and metallization shading typically contribute a significant fraction to the total power loss for these devices. In flat silicon photovoltaic (PV) modules, the front‐metal finger shape is often shaped to minimize shading losses. Finger shape is even more relevant for CPV cells where the current density and front metal shading are much higher. This study compares the optical performance of five light management finger designs in CPV systems with two different refractive homogenizers. The optical efficiency and loss analysis were determined using ray‐tracing simulations. It is shown that shaped, light diverting metal fingers can improve the optical efficiency in CPV systems by up to 9.9% absolute compared to rectangular fingers, corresponding to an absolute cell efficiency increase of 3.0%. Although sharp edged triangular finger structures may be challenging to fabricate, significant optical gains can still be achieved with trapezoid or rounded cap finger shapes.

Towards high-efficiency Al-BSF c-Si solar cell with both superior omnidirectional and electrical performance by modulating the tilt angle of quasi-periodic inverted pyramid arrays

Seeking efficient light trapping structures with both superior omnidirectional and electrical performance is always on the way for increasing electrical energy output of c -Si solar cell over a wide range of light incident angle (θ). Here, tile angle (δ) of quasi-periodic structure arrays is systematically modulated from 35.9° to 72.8° on diamond-wire-sawn (DWS) c -Si by a simple and cost-effective Cu and Ni co-assisted chemical etching way followed by a post treatment. Interestingly, compared with the conventional micro pyramid (MP), the optimized inverted pyramid (IP) like arrays with a δ of 64° possess both lower light reflectance and carrier recombination, leading to a corresponding solar cell with a higher efficiency (∼19.67%) than that of MP based counterpart (∼19.31%). Moreover, during the increase of θ, the external quantum efficiency (EQE) of 64° IP based cell drops much more slowly than that of MP based one by properly adjusting the relative position of the structure arrays and incident light, indicating its omnidirectional property. Simultaneously, a maximum relative enhancement of electrical output power approaching ∼5.8% in the θ range of −90°–90° is achieved on 64° IP based cell compared to the MP based one, the mechanism behind which is further explained by optical simulation. The above finds pave a new way to increase the electrical energy output in a simple and cost-effective way. • Tilt angle control of quasi-periodic IP was achieved by varying Cu and Ni ratio. • 0.36% absolute increase in solar cell efficiency was made based on 64° IP. • ∼5.8% relative increase of output power was achieved on 64° IP based cell. • Mechanism behind omnidirectional performance was explained by optical simulation.

Novel application of lignin biopolymer for radiative cooling

Conventional plastics and composites that we mostly use are derived from petroleum which is a non-renewable resource. Plenty of these plastics are designed for a single purpose and end up in landfills, causing significant environmental impact since the degradation rate is extremely slow and can take centuries. On the other hand, biopolymers are sustainable, yearly renewable, and environment-friendly solution to the current problem associated with conventional plastics. In this paper, lignin, a biodegradable polymer derived from wood, has been utilized for radiative cooling applications. In this radiative cooling process, an optimized structure exchanges heat with the surrounding environment and can effectively cool down to a temperature below ambient temperature. Here we are reporting a lignin-upgraded polymer film that shows a cooling power of 77 W/m2 under direct sunlight irradiance and achieves a surface temperature that is 3.7 °C below the ambient temperature. Integrating this structure with solar cell has reduced the operating temperature of the cell by 3 °C while showing an absolute efficiency increase of 0.45% compared to the reference cell under the AM1.5G solar spectrum. This approach can easily be applied to a large area at a low cost and is a significant step forward for the large-scale implementation of radiative cooling technology.

Characterization of Plasmonic Scattering, Luminescent Down-Shifting, and Metal-Enhanced Fluorescence and Applications on Silicon Solar Cells.

This paper studied characterized the plasmonic effects of silver nanoparticles (Ag-NPs), the luminescent down-shifting of Eu-doped phosphor particles, and the metal-enhanced fluorescence (MEF) achieved by combining the two processes to enhance the conversion efficiency of silicon solar cells. We obtained measurements of photoluminescence (PL) and external quantum efficiency (EQE) at room temperature to determine whether the fluorescence emissions intensity of Eu-doped phosphor was enhanced or quenched by excitation induced via surface plasmon resonance (SPR). Overall, fluorescence intensity was enhanced when the fluorescence emission band was strongly coupled to the SPR band of Ag-NPs and the two particles were separated by a suitable distance. We observed a 1.125× increase in PL fluorescence intensity at a wavelength of 514 nm and a 7.05% improvement in EQE (from 57.96% to 62.05%) attributable to MEF effects. The combined effects led to a 26.02% increase in conversion efficiency (from 10.23% to 12.89%) in the cell with spacer/NPs/SOG-phosphors and a 22.09% increase (from 10.23% to 12.48%) in the cell with spacer/SOG-phosphors, compared to the bare solar cell. This corresponds to an impressive 0.85% increase in absolute efficiency (from 12.04% to 12.89%), compared to the cell with only spacer/SOG.

Efficiency improvement of passivated emitter and rear cells using annealing process before surface passivation

Thermal annealing and effective surface passivation are significant to achieve high conversion efficiency (η) of passivated emitter and rear cells (PERC). Thus, we added an annealing process before front and rear surface passivation in the existing production line. We found that the front recombination current (J0,f) and the rear recombination current (J0,r) of annealed PERCs are both lower than baseline PERCs without annealing process, which means better defect repair and passivation effect were achieved. And the average η of annealed PERCs reaches 21.79%, which is 0.23% absolutely higher than that of the baseline PERCs. After that, we further explored the influence of gas composition (0%, 5% and 10% oxygen concentration in nitrogen atmosphere) during annealing process. We found that as the oxygen concentration increases, J0,fs and J0,rs of annealed PERCs (0%, 5%, 10%) are all lower than those of baseline PERCs. Meanwhile, the annealed PERCs (0%, 5%, 10%) get the average η of 21.77%, 21.82% and 21.84% respectively, possessing absolute efficiency increase over the baseline PERCs with the average η of 21.67%. The present work could help enhance the understanding of passivation property and improve the performance of industrial PERC cells.

Analysis of the negative charges injected into a SiO2/SiNx stack using plasma charging technology for field‐effect passivation on a boron‐doped silicon surface

AbstractWe investigated field‐effect passivation by injecting negative charges into SiO2/SiNx stack using a plasma charge injection technique. The Si/SiO2/SiNx samples exhibited a very high flat‐band shift with a high injected negative charge density (>3.0 × 1013 cm2) after plasma negative charge injection; this density was higher than that for the well‐known Al2O3 layer. Most injected negative charges were present within approximately 90 nm of the surface of the SiNx layer deposited by plasma‐enhanced chemical vapor deposition (PECVD) when comparing the capacitance–voltage analysis results obtained while etching the SiNx film considering four assumptions of the injected negative charge distribution. The saturation current density in a 90‐ohm/sq boron emitter decreased from ~90 to 50 fA/cm2 after negative charge injection, which is equivalent to the J0e of the structure passivated with an Al2O3/SiNx stack. Six‐inch n‐type bifacial cells with an approximately 100‐ohm/sq boron emitter passivated with SiO2/SiNx displayed an approximately 0.2% increase in absolute cell efficiency after negative charge injection. In addition, n‐PERT bifacial cells with a high boron sheet resistance of ~150 ohm/sq exhibited a 1.0% or higher absolute efficiency enhancement from a relatively low precharging efficiency of approximately 19.0%. We also demonstrated that the final efficiency after charging was comparable with n‐PERT bifacial cells with Al2O3 passivation, suggesting that the proposed process is a potential low‐cost alternative method that could replace expensive Al2O3 processes.

Understanding how chlorine additive in a dynamic sequential process affects FA0.3MA0.7PbI3 perovskite film growth for solar cell application

In this work, for the first time, we identify the effect of adding chlorine (Cl) in the dynamic sequential (no stoppage between the sequential steps and the precursor for the second-step is dispensed while the substrate is in motion) solution processing of formamidinium methylammonium lead iodide FA0.3MA0.7PbI3 perovskite solar cells by comparing (i) the roles of two different Cl sources (MACl and FACl) and (ii) the time at which the Cl sources were added: (a) into PbI2-DMSO in the first deposition step or (b) into MAI-FAI in the second deposition step. It is found that Cl in general (regardless of the type of source and at which step it is added) improves the perovskite film with better coverage, better crystallinity, and higher photoluminescence response and longer carrier lifetime due to reduced trap densities. Characterizations for investigating film formation mechanisms reveal that the amount of Cl remaining in the final film is most crucial in determining the film quality. This in turn is controlled by when Cl is added. When Cl is added in the second step, the higher Cl content which is highly diffusive initiates the Dimethyl sulfoxide (DMSO) complex formation and perovskite formation too rapidly producing films with excess PbI2, which are more disorder and have lower crystallinity. FACl exacerbates this while MACl reduces the detrimental effect by slowing down perovskite formation. Therefore, for dynamic sequential processing, it is recommended that MACl is used as the preferred source over FACl and Cl should be added in the 1st step of the process allowing sufficient Cl to leave the film in the 2nd step of the sequential process. The resulting film has better film quality producing a champion device with a 2.8% absolute efficiency increase over the best device fabricated without Cl additives. This work has provided great insights into the film formation mechanism by sequential processing with additive engineering.

Numerical Modeling of a Photovoltaic/Microchannel Direct-Expansion Evaporator for a CO2 Heat Pump

Abstract A numerical model of a PV/microchannel direct-expansion evaporator for a CO2 heat pump is developed and validated with experimental data from the literature. The effects of degree of superheating, CO2 mass flux, and evaporation temperature on the amount of heat absorbed, pressure drop in the microchannel evaporator, PV temperature, and electrical efficiency are analyzed. The analysis shows that increasing the degree of superheating decreases the amount of heat absorbed, has minimal effect on the PV temperature (for superheating <15 °C), but reduces the pressure drop. The variation of CO2 mass flux has a minimal effect on the amount of heat absorbed and the PV temperature, but the pressure drop increases with increasing CO2 mass flux. Increasing the evaporation temperature decreases the amount of heat absorbed, reduces the pressure drop, and increases the PV temperature. For average ambient conditions for Fargo, North Dakota, a 5–10 °C of superheating at the evaporator outlet, an evaporator temperature between −5 and +5 °C, and a CO2 mass flux of 330–550 kg · m−2 · s−1 balance maximizing the heat absorption while minimizing the pressure drop. To maximize the PV efficiency, lower evaporation temperatures should be used. At an evaporation temperature of 0 °C and an insolation level of 1000 W · m−2, the CO2 microchannel evaporator causes a 23 °C reduction in PV panel temperature which corresponds to a 1.44% absolute increase in PV efficiency.

Interface analysis of Ag/n‐type Si contacts in n‐type PERT solar cells

AbstractTo increase efficiencies of bifacial solar cells, emitter, back surface field (BSF), and metal patterns must be optimized. We study the influence of paste volume, through multiple prints, of two silver pastes on the contact formation at the rear side of n‐type passivated emitter and rear totally diffused (n‐PERT) solar cells with two BSF doping profiles. Differences in fingers' electrical properties were found between pastes. Contact resistivity shows a relative difference of 27.6%, partially explained by changes in the silver crystallites formation at the Ag/Si interface and in the crystallites' penetration depth. Variations in crystallites formation and penetration between pastes can reach 38.4% and 48.8%, respectively. Line resistance shows a difference between pastes, appearing as the main cause of an absolute efficiency difference of 2.9%. Fingers' structural and electrical properties are modified by increasing the paste volume. Microstructure analysis reveals that additional metallic printing does not only increase line cross sectional area but also increases the formation of silver crystallites, which can reach a relative increment of 23.9% between first and second prints. Further printing does not necessarily decrease contact resistivity, but reduces line resistance in up to 94.9%, which results in an absolute efficiency increase of 2.2%. In addition, the higher presence of silver oxide in the finger is related to a higher efficiency in the formation of silver crystallites. Finally, BSF doping has an influence in the open circuit voltage, short circuit current density, and contact resistivity, with differences that can reach 8.7 mV, 0.2 mA/cm2, and 6.1 mΩcm2, respectively, depending on paste and number of prints.

Tracking-free adaptive contact concentration photovoltaics

Adaptive Contact Concentration Photovoltaics (ACCPV) is outlined as a scheme to access CPV efficiency improvements without mechanical tracking. This could allow CPV to play a role in applications where maintenance-free reliability and compact size are essential requirements. Conversion efficiency enhancement using sunlight concentration in multi-junction or potentially single junction solar cells due to the well-known increase in the Shockley-Quessar limit are enabled by replacing a tracking system with an array of switchable electrodes. Cell electrodes are segmented and are connected employing a switching system that adapts to sunlight conditions. Unlike CPV systems, the ACCPV concept allows for effective operation in diffuse sunlight conditions. System losses that must be considered in order to determine whether a net benefit for ACCPV exists for a given solar cell type include optical losses, series resistance losses, and Auger losses. The ACCPV concept is clearly presented and relevant system losses are discussed. A 3% absolute increase in triple junction cell efficiency is projected.

Glancing angle deposited CdTe: Nanostructured films and impact on solar cell performance

Cadmium telluride (CdTe) thin films with different microstructures and optical properties have been produced on soda-lime glass by glancing angle deposition (GLAD) at oblique sputtering angles varying from 0° to 80° with respect to the substrate normal. From cross-sectional scanning electron micrographs, increasingly tilted columnar structure occurs with increasing incident angle for as-deposited CdTe films. CdTe films deposited at lower angles closer to normal incidence consist of a mixture of cubic zinc blende and hexagonal wurtzite crystal structures while films prepared at more oblique angles have hexagonal wurtzite crystal structure. Post-deposition CdCl2 treated films show enhancement in crystallite/grain size for samples prepared under all conditions. The optical response in the form of the complex dielectric function (ε = ε1 + iε2) spectra from 0.74 to 5.89 eV for the GLAD thin films are all qualitatively similar to single crystal CdTe. Higher angle deposited samples show columnar structure induced anisotropy in spectra in ε in the transparent spectral range. Application of GLAD CdTe interlayers between CdS and CdTe of the standard CdS/CdTe heterojunction design solar cell shows better performance with up to 0.9% absolute efficiency increase.

Spectral-temporal study on the output power of green InGaN LEDs

To mitigate the “green gap” effect in green light-emitting diodes (LEDs), we investigate a pulsed mode operation, where carrier injection and carrier recombination happen at different bias. Carriers are injected into the quantum wells during forward bias, and recombine during reverse bias when the overlap of electron and hole wave functions is maximized. For this, we investigate the spectral-temporal properties of commercial green LEDs during pulsed operation with varying forward current from 2,5 up to 70 mA and reverse bias from 0 to −3 V. At the falling edge of the electrical signal an increase of the intensity and blue-shift of the emission could be demonstrated, indicating the dynamic reduction of the quantum-confined stark effect. However, droop curves measured in pulsed mode did not show an absolute improvement in efficiency, compared to cw droop curves. We conclude that green LEDs have to be optimized for this mode of operation to show an absolute increase in efficiency in pulsed mode.

Experimental Investigation of Fuel Anti-Knock-Index Requirements in Three Small Two-Stroke Engines for Remotely Piloted Aircraft

Small remotely piloted aircraft (10–25 kg) that are powered by internal combustion engines typically operate on gasoline with an anti-knock index (AKI) > 80. To comply with the single-battlefield-fuel initiative [Department of Defense (DoD) Directive 4140.25], interest has increased in converting power plants for these platforms to run on low-AKI fuels such as diesel and Jet-A with AKIs of ∼20. It has been speculated that the higher losses (short circuiting, incomplete combustion, heat transfer) that cause these engines to have lower efficiencies than their conventional-scale counterparts may also relax their required fuel AKI. The fuel-AKI requirements of three two-stroke spark ignition (SI) engines with 28, 55, and 85 cm3 displacements were mapped, and the performance was compared to that on 98 ON (octane number) fuel. Switching from 98 ON fuel to 20 ON (Jet-A and diesel equivalent AKI) fuel while maintaining optimum combustion phasing led to a 3–5 crank-angle degree (CAD) reduction in burn angle, a 2–3% increase in power, and a 0.5–1% (absolute) increase in fuel-conversion efficiency at non-knock-limited conditions through shortening of the CA0–CA10 burn angle. The efficiency improvement translates to a 6% increase in range or endurance. The results indicate that abnormal combustion is not a significant obstacle to operating small commercial-off-the-shelf (COTS) engines on low-AKI fuels and that most of the power and efficiency improvements demonstrated in previous heavy-fuel conversion efforts were the result of modifications made to accommodate low-volatility fuels, not the faster burn rate of the low-AKI fuels themselves.

Age-adjusted cut-off using the IL D-dimer HS assay to exclude pulmonary embolism in patients presenting to emergency.

The ADJUST-PE study showed that an age-adjusted D-dimer (AADD) (age years × 10 ng/mL if >50 years) combined with an unlikely pre-test probability (PTP) can increase the proportion of older patients in whom pulmonary embolism (PE) can be safely excluded, but the IL D-dimer HS assay was not assessed. To assess the ability of the IL D-dimer HS assay to exclude PE using the AADD. Retrospective analysis of consecutive patients presenting with symptoms of acute PE to one of three Monash Health Emergency Departments (January 2013-January 2014) who had computed tomography pulmonary angiography. In the group with D-dimer, efficiency (proportion of PE excluded based on a combination of unlikely PTP and negative D-dimer) was determined using (i) current laboratory (200 ng/mL), (ii) conventional (230 ng/mL) and (iii) modified (375 ng/mL if age ≥60 years) AADD cut-offs. A total of 176 patients with D-dimers was included (mean age = 58.5 years; 54.0% males; 71.0% age >50 years). Prevalence of PE in the overall, unlikely and likely PTP groups, was 17.0, 13.0 and 24.6% respectively. In the unlikely PTP group (115 patients), efficiency for the current, conventional, modified and AADD cut-offs was 9.6, 24.3, 30.4 and 37.4% respectively. The absolute increase in efficiency of an AADD compared to conventional cut-off using the IL D-dimer HS assay is modest (~10%) and requires prospective validation. Modifying our cut-off to 230 ng/mL and systematic implementation of a clinical algorithm, including D-dimer testing and PTP, is likely a more important first step.