Filter by: All | OLED | Solar Cell | Light Scattering | Drift Diffusion | Optics | Perovskite | Batteries | OLEC | Stability | Photodetectors
E. Benvenuti, A. Lanfranchi, S. Moschetto, M. Natali, M. Angelini, P. Lova, F. Prescimone, V. Ragona, D. Comoretto, M. Prosa, M. Bolognesi and S. Toffanin,
J. Mater. Chem. C, 2024,
This paper presents the development of an all-organic, on-chip integrated system for fluorescence detection, combining organic photodiodes (OPDs), organic light-emitting diodes (OLEDs), and a polymeric distributed Bragg reflector (DBR) filter. By integrating these components on a single substrate, the system offers a compact and efficient solution for fluorescence sensing, which is crucial for applications ranging from food safety to environmental monitoring. The use of organic materials allows for low-cost, flexible sensors that can be easily produced and deployed. The paper demonstrates that this integrated approach significantly enhances the optical efficiency and sensitivity of the fluorescence sensor, making it capable of detecting concentrations as low as 9.2 μM of the model dye Rhodamine 700. This advancement represents a significant step towards the development of portable, high-performance sensors for point-of-need applications
How Sefos was used
Setfos was used to design the OLED structure to achieve an efficient and narrow phosphorescent emission, crucial for the integrated fluorescence sensor's performance. The simulation helped in fine-tuning the composition and thickness of the OLED's interlayers, including an organic index matching layer, to enhance light extraction and emission characteristics tailored to the absorption spectrum of the fluorescent dye, Rhodamine 700.
Darshan H. Parmar, Benjamin Rehl, Ozan Atan, Sjoerd Hoogland, and Edward H. Sargent
ACS Applied Materials & Interfaces Article ASAP
DOI: 10.1021/acsami.3c14611
Colloidal quantum dot photodetectors exceed silicon's limits by detecting longer wavelengths, with performance depending on the ligand concentration during processing. This study connects simulated and actual photocurrent responses, showing that different ligand concentrations uniquely impact trap state density and device behavior.
How Setfos was used
Setfos was used to show how the transient measurements were consistent with a changing trap density in the photodetector active layer with respect to ligand exchange concentration.
Yu Zhang, Weiqing Nie, Mengli Hu, Wu Liu, Heng Liu, Xiaomin Huo, Yao Lu, Dandan Song, Bo Qiao, Zhiqin Liang, Zhiqiang Jiao, Zheng Xu, Guangcai Yuan, and Suling Zhao
ACS Photonics 2023 10 (10), 3521-3530
https://doi.org/10.1021/acsphotonics.3c00524
This research outlines the advancement in tandem optoelectronic devices, specifically a perovskite/organic quasi-tandem system for narrowband photodetectors (NPDs) targeting the visible to near-infrared spectrum. By varying the composition of perovskite and organic layers, the spectral response is tunable, enhancing device selectivity and flexibility. Achieving a peak response near 790 nm with a 41 nm bandwidth, these NPDs exhibit rapid submicrosecond response times, significantly outperforming traditional thick-layer photodetectors, marking a step forward in the development of ultra-fast NPDs.
How Setfos was used
Setfos was utilized to stimulate the penetration of different monochromatic light, the thickness of perovskite (MAPbI3) was set as 1700 nm, and a 150 nm of organic blend layer (PM6:IT-4F) was set on the perovskite. Take thickness as the scanning parameter, with a step size of 10 nm. The optical parameters (n, k) of the materials are obtained through an ellipsometer.
Jinno, H., Shivarudraiah, S. B., Asbjörn, R., Vagli, G., Marcato, T., Eickemeyer, F. T., Pfeifer, L., Yokota, T., Someya, T., Shih, C.-J.,
. Adv. Mater. 2023, 2304604.
https://doi.org/10.1002/adma.202304604
This research presents a breakthrough in ultrathin, flexible skin optoelectronics for Internet of Things (IoT) applications. Traditional issues like underperformance due to low polymer process temperatures and spectral distortion from bending are overcome using solution-processed perovskite semiconductors. The study introduces high-efficiency perovskite solar cells and LEDs on polymer films with exceptional thermal stability, achieving record efficiencies (18.2% for solar cells, 15.2 cd A−1 for LEDs) and bending-resistant light emission. This advancement enables reliable, high-performance, self-powered wearables and IoT sensors, demonstrating practical applications such as accurate pulse monitoring at a high selectivity rate.
How Setfos Was used
Finite element analysis for ultraflexible LED was simulated with the Setfos emission module. By expecting the dipole emission model of LED, the module allows to deliver emission spectra of ultraflexible LED with different angle.
Abu Bakar Siddik, Epimitheas Georgitzikis, Yannick Hermans, Jubin Kang, Joo Hyoung Kim, Vladimir Pejovic, Itai Lieberman, Pawel E. Malinowski, Andriy Kadashchuk, Jan Genoe, Thierry Conard, David Cheyns, and Paul Heremans
ACS Applied Materials & Interfaces 2023 15 (25), 30534-30542
DOI: 10.1021/acsami.3c03708
This study presents a high-speed, low dark current near-infrared organic photodetector (NIR OPD) on a silicon substrate using amorphous indium gallium zinc oxide (a-IGZO) as the electron transport layer (ETL). Detailed characterization reveals the dark current mechanism as trap-assisted field-enhanced thermal emission, significantly reduced by introducing an interfacial layer. The NIR OPD achieves a low dark current of 125 pA/cm² at -1 V reverse bias and boasts a rapid photo response time, making it suitable for high-quality sample image capture in an imager on a complementary metal oxide semiconductor read-out circuit.
How Paios was used
Q-DLTS and TPV decay measurements were performed using Paios.
Lee, J., Georgitzikis, E., Hermans, Y. et al.
Nat Electron 6, 590–598 (2023).
https://doi.org/10.1038/s41928-023-01016-9
Thin-film image sensors with pinned photodiode structures, using organic or colloidal quantum dot photodiodes, demonstrate noise performance comparable to silicon-based counterparts. These sensors exhibit low noise, reduced dark current, high capacity, and efficient electron-to-voltage conversion. For instance, an organic absorber-based sensor achieves 54% quantum efficiency at 940 nm with 6.1e– read noise.
How Paios was used
The transient photoresponse, photocurrent linearity and capacitance–voltage measurements were performed using a Paios all-in-one system by Fluxim.
Kamijo, T., van Breemen, A.J.J.M., Ma, X. et al. A touchless user interface based on a near-infrared-sensitive transparent optical imager. Nat Electron (2023).
https://doi.org/10.1038/s41928-023-00970-8
Researchers have developed a touchless user interface based on a visually transparent near-infrared-sensitive organic photodetector (OPD) array. The touchless interface can be used on top of a display, eliminating the need for physical contact.
The OPD array is designed with optical transparency in mind, using printed copper grids and patterned organic photodetector subpixels. The design optimization results in a high photodetectivity of 10^12 Jones at 850 nm and a visible-light transmittance of 70%.
The touchless user interface can be used with a penlight or through gesture recognition, providing a hygienic and convenient alternative to traditional touch screens. The technology has potential applications in automated teller machines (ATMs), ticket vending machines, and kiosks, where hygiene is a concern. It is a scalable and flexible solution that can be integrated into a variety of display applications without size limitations or calibration requirements. 2D FEM simulations for the surface potential and the current density distributions derived from the printed Cu grid structure .
How Fluxim’s Research Tools were used
Setfos
Numerical electro-optical simulations for the photogenerated J–V curves of our NIR-sensitive OPDs were performed by using Setfos.
The VLT of the parallel OPD subpixel array was calculated by the summation of the simulated optical transmittance for each component using Setfos
Laoss
2D FEM simulations for the surface potential and the current density distributions derived from the printed Cu grid structure for our NIR-sensitive OPDs were performed by Laoss 4.0
haoyang Wang et al 2023 J. Phys. Mater. 6 024004
Indoor photovoltaic devices using halide perovskites are studied for their potential in powering IoT applications. CH3NH3PbI3-based devices with Spiro-OMeTAD and P3HT as hole transport layers were compared, and Spiro-OMeTAD showed higher power conversion efficiency. The best-performing Spiro-OMeTAD device successfully powered a wearable motion sensor, demonstrating the potential for self-sufficient sensor systems.
Light intensity-dependent J-V measurement, transient photovoltage (TPV) and transient photocurrent (TPC) measurement were carried out with the characterization platform, Paios, Fluxim AG, Switzerland.
Metikoti Jagadeeswararao, Kyu Min Sim, Sangjun Lee, Mingyun Kang, Sanghyeok An, Geon-Hee Nam, Hye Ryun Sim, Elham Oleiki, Geunsik Lee, and Dae Sung Chung
Chemistry of Materials 2023 35 (8), 3095-3104
DOI: 10.1021/acs.chemmater.2c03271
This study demonstrates high-performance photomultiplication (PM)-type photodetectors using lead-free double perovskite, achieved by engineering trap states and trap-assisted charge injection. With a diode structure, the researchers realized selective hole traps, leading to high external quantum efficiency (EQE) of ∼16,000%, responsivity of ∼50 A W−1, and specific detectivity over 10¹² Jones at -3V. The work highlights PM photodetectors' potential through strategic trap engineering.
Setfos, a Fluxim software, was used for drift-diffusion simulations to gain comprehensive insight into the photomultiplication mechanism in the proposed photodetector.
Li, B., Huang, X., Wu, X., Zuo, Q., Cao, Y., Zhu, Q., Li, Y., Xu, Y., Zheng, G., Chen, D., Zhu, X.-H., Huang, F., Zhen, H., Hou, L., Qing, J., Cai, W., Adv. Funct. Mater. 2023, 2300216. https://doi.org/10.1002/adfm.202300216
Q-2D perovskites are promising photodetector materials, but their charge transport is limited by their hybrid low-dimensional structure. Researchers used a double-hole transport layer (PTAA & PEDOT:PSS) to create evenly-distributed 3D-like phases with vertical orientation, improving charge transport and reducing recombination.
This Ruddlesden-Popper perovskite photodetector achieved a high responsivity, specific detectivity, linear dynamic range, and fast rise/fall times. The study reveals the relationship between Q-2D perovskites' phase structure and performance, guiding future photodetector designs.
Transient photovoltage decay (TPV) measurements were performed with PAIOS instrumentation.
Andrés-Felipe Castro-Méndez, Jamie P. Wooding, Selma Fairach, Carlo A. R. Perini, Emily K. McGuinness, Jacob N. Vagott, Ruipeng Li, Sanggyun Kim, Vivek Brahmatewari, Nicholas Dentice, Mark D. Losego, and Juan-Pablo Correa-Baena
ACS Energy Lett. 2023, 8, 1, 844–852
Publication Date: January 3, 2023
https://doi.org/10.1021/acsenergylett.2c02272
This study investigates the use of vapor phase infiltration (VPI) to improve the stability of organic charge transport layers, such as hole-selective spiro-OMeTAD in perovskite solar cells (PSCs) and other organic electronic devices.
By using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and grazing incident wide-angle X-ray scattering (GIWAXS), the study identifies that infiltration of TiOx via VPI hinders the crystallization of the spiro-OMeTAD layer. The infiltrated PSCs retained over 80% of their original efficiency after an operando stability test of 200 hours at 75°C, double the efficiency retained by devices without infiltration. This study suggests VPI can be used to stabilize organic charge transport layers and prolong device lifetimes.
Device stability measurements were carried out by tracking the maximum power point (MPP) of the devices while keeping constant the temperature of the films (by Peltier pads) at 75 °C using the stability measurement platform Litos from Fluxim.
Steele, J.A., Braeckevelt, T., Prakasam, V. et al.
Nat Commun 13, 7513 (2022).
https://doi.org/10.1038/s41467-022-35255-9
The black perovskite phase of CsPbI3 is promising for optoelectronic applications; however, it is unstable under ambient conditions, transforming within minutes into an optically inactive yellow phase, a fact that has so far prevented its widespread adoption.
In this paper the research team present an effective strategy for embedding an interfacial microstructure (a PbI2 microgrid) into stable CsPbI3 perovskite thin films and devices, using a coarse photolithographic approach. The microgrid is shown to dramatically increase the long-term stability of black CsPbI3 thin films (beyond 2.5 years in a dry environment) by increasing the phase transition energy barrier (Eb) and limiting the spread of potential yellow phase formation to a single, isolated domain of the grid.
Using stabilized photodetectors, integration of a microgrid into normally unstable planar CsPbI3 perovskite devices is shown to be a simple and effective strategy toward stable ambient operation.
Paios was used to measure the rise and decay time and the capacitance of the devices. The pulsed J-V characteristics were measured from 2 V to −1 V with 50 ms, 1 ms, and 25 ms as the pulse length, rise time, and measurement time, respectively.
Kunsik An, Chaewon Kim, Kwan Hyun Cho, Seunghwan Bae, Bo Kyung Cha, Kyung-Tae Kang,
Organic Electronics, Volume 100, 2022, 106384
doi.org/10.1016/j.orgel.2021.106384
An X-ray detector system was fabricated with an organic small molecule photodetector and a terbium-doped gadolinium oxysulfide (Gd2O2S:Tb) scintillating screen. Though the microsphere cluster structure of the Gd2O2S film had advantage in low material cost, wavelength matching to the proper photodetector is challenging due to its scintillating performance property in the relatively narrow emission spectrum range.
This work, including the spectral tuning using the strong microcavity effect and X-ray detection for medical applications, will provide new insights for the further development of OPDs.
The optical calculation of the absorption spectra was carried out using SETFOS. The optical constants n (refractive index) and k (absorption index) were obtained from the software.
Palepu Ashok, Jay Chandra Dhar
2022 International Conference for Advancement in Technology (ICONAT), 2022, pp. 1-6,
doi: 10.1109/ICONAT53423.2022.9725852.
Here the researchers designed an HTL free photo detector with ZnO as an electron transport layer (ETL) fabricated using RF sputtering and the perovskite material CH3NH3PbI3 as a light absorbing material deposited using two-step spin coating method.
The performance of the device is modelled by using SETFOS software with the impedance spectroscopy technique by changing different metal electrodes like, Ag, Au, Pd and Pt. Among all, the Pt electrode showed high current density (18.6914 mA/cm^2), high fill factor (0.558) and maximum power conversion efficiency (18.5%).
Qiwei Xu, I. Teng Cheong, Hanfa Song, Vien Van, Jonathan G. C. Veinot, and Xihua Wang
ACS Photonics 2022, 9, 8, 2792–2801
doi/pdf/10.1021/acsphotonics.2c00587
Integrating lead sulfide (PbS) colloidal quantum dots (CQDs) with crystalline silicon (c-Si) has been proven to be an effective strategy in extending the sensitivity of Si-based photodetectors into infrared regime. Here, the research team demonstrate the successful integration of PbS CQD inks with Si and construct a highly efficient heterojunction infrared photodiode operating in the range from 800 up to 1500 nm.
Summary points:
∙PbS CQD on Si to increase sensitivity of Si to IR
∙CQD:Si photodetector operating from 800 to 1500 nm
∙Layer of p-type QD enhances built-in electric field
∙EQE of 44% at 1280nm and 2V reverse bias - stable for more than 600 h
∙Photoresponse lower than 4μs without tails indicate low trap density
Lead sulfide (PbS) colloidal quantum dots (CQD) enable Si photodector sensitivity in the near infrared (NIR) in the range from 800 to 1500 nm.
The group of Xihua Wang at the University of Alberta achieved this result by spin-coating PbS CQD to form a CQD:Si heterojunction photodetector. The addition of a p-type CQD buffer layer at the CQD:Si interface enhanced the built-in electric field and improved the charge extraction. With transient photocurrent (TPC) and photovoltage (TPV) they measured a photoresponse lower than 4μs demonstrating low trap density at the CQD:Si interface.
TPC and TPV measurements were possible thanks to the all-in-one characterization platform PAIOS from Fluxim AG.
Leemans, J., Pejović, V., Georgitzikis, E., Minjauw, M., Siddik, A. B., Deng, Y.-H., Kuang, Y., Roelkens, G., Detavernier, C., Lieberman, I., Malinowski, P. E., Cheyns, D., Hens, Z.
Adv. Sci. 2022, 9, 2200844.
doi.org/10.1002/advs.202200844
QD-photodetectors are cost-effective, have small pixel pitch, and high spectral tunability, but they generally rely on restricted elements such as Pb and Hg. The team at Ghent University and imec fabricated high-efficiency photodetectors with non-restricted In(As,P) QDs deposited by spin-coating. These devices exhibit the best internal quantum efficiencies at the QD band gap of 46±5% and are sensitive to SWIR light up to 1400 nm.
Paios was used to characterize the photodetectors both in DC and transient modes. Thanks to all co-authors for your trust in our products.
Wei-Hsu Hu, Camilla Vael, Matthias Diethelm, Karen Strassel, Surendra B. Anantharaman, Abdessalem Aribia, Marco Cremona, Sandra Jenatsch, Frank Nüesch, and Roland Hany
Adv. Optical Mater. 2022, 2200695
Organic upconversion devices (OUCs) consist of an organic infrared photodetector and an organic visible light-emitting diode (OLED), connected in series. OUCs convert photons from the infrared to the visible and are of use in applications such as process control or imaging.
Many applications require a fast OUC response speed, namely the ability to accurately detect in the visible a rapidly changing infrared signal.
Here, high image-contrast, narrowband OUCs are reported that convert near-infrared (NIR) light at 980 and 976 nm with a full-width at half maximum of 130 nm into visible light. Transient photocurrent measurements show that the response speed decreases when lowering the NIR light intensity. This is contrary to conventional organic photodetectors that show the opposite speed-versus-light trend.
It is further found that the response speed increases (when using a phosphorescent OLED) or decreases (for a fluorescent OLED) when increasing the driving voltage.
To understand these surprising results, an analysis by numerical simulation is conducted. Results show that the response speed behavior is primarily determined by the electron mobility in the OLED. It is proposed that the low electron drift velocity in the emitter layer sets a fundamental limit to the response speed of OUCs.
Optical and electrical simulations were performed with Setfos 5.2
Vladimir Pejović, Epimitheas Georgitzikis, Itai Lieberman, Paweł E. Malinowski, Paul Heremans, David Cheyns
Adv Funct. Mat., (2022)
https://doi.org/10.1002/adfm.202201424
Image sensors based on colloidal quantum dots (CQDs) are expected to deliver affordable infrared image sensors to wider application scope. Here, a dual-band photodetector based on PbS CQDs is presented. By engineering the surface of CQDs, two oppositely facing pn junctions are fabricated in series, which enable sensing in two spectral channels. The presented photodetectors exhibit low dark current below 500 nA cm−2 at 1 V bias, a fast response measured in microseconds, as well as high external quantum efficiency, reaching 70% in NIR and 30% in SWIR.
Mingyun Kang, Syed Zahid Hassan, Seong-Min Ko, Changwon Choi, Juhee Kim, Santosh K. R. Parumala, Yun-Hi Kim, Yun Hee Jang, Jinhwan Yoon, Dong-Woo Jee, Dae Sung Chung
Advanced Materials
doi.org/10.1002/adma.202200526
When the intensity of the incident light increases, the photocurrents of organic photodiodes (OPDs) exhibit relatively early saturation, due to which OPDs cannot easily detect objects against strong backlights, such as sunlight. In this study, this problem is addressed by introducing a light-intensity-dependent transition of the operation mode, such that the operation mode of the OPD autonomously changes to overcome early photocurrent saturation as the incident light intensity passes the threshold intensity. The photoactive layer is doped with a strategically designed and synthesized molecular switch, 1,2-bis-(2-methyl-5-(4-cyanobiphenyl)-3-thienyl)tetrafluorobenzene (DAB). The proposed OPD exhibits a typical OPD performance with an external quantum efficiency (EQE) of <100% and a photomultiplication behavior with an EQE of >100% under low-intensity and high-intensity light illuminations, respectively, thereby resulting in an extension of the photoresponse linearity to a light intensity of 434 mW cm?2. This unique and reversible transition of the operation mode can be explained by the unbalanced quantum yield of photocyclization/photocycloreversion of the molecular switch. The details of the operation mechanism are discussed in conjunction with various photophysical analyses. Furthermore, they establish a prototype image sensor with an array of molecular-switch-embedded OPD pixels to demonstrate their extremely high sensitivity against strong light illumination.
To further verify the effect of DAB_c on gain generation, the researchers conducted a numerical simulation using the Fluxim’s Setfos software to fit the experimentally obtained OPD data and determine the relevant fitting parameters.
Xu, Qiwei; Cheong, I Teng; Meng, Lingju; Veinot, Jonathan G. C.; Wang, Xihua
ACS Nano 2021, 15, 11, 18429–18436.
doi.org/10.1021/acsnano.1c08002
In this paper the researchers test different Si passivation tricks to optimize PbS quantum dot detectors. The two-step passivation device shows an EQE of 31% at 1280 nm and -4V.
Paios was used to perform TPV and TPC measurements to confirm longer lifetime and faster extraction, respectively, using the two-step process. This is explained by trap passivation.
