From our measurements we obtain both electron and hole mobilities, and show that these values are carrier concentration dependent. Most unusually, the electron mobility displays a negative Poole-Frenkel effect. Numerical modeling of the lateral structure shows that accounting for the Poole-Frenkel behavior has a significant effect on charge carrier behavior within the channel. Applying numerical modeling to vertical OSCs demonstrates that results from lateral structures provide insight into charge transport in in structures employed for collecting sunlight.
Efficient perovskite solar cells employing polymers as effective hole transport layer Canceled Paper Author s : Show Abstract. Perovskite based solar cells have shown to be an highly efficient solution processable device, because of its broad band light absorbing property and high charge diffusion length. However, a long term stable perovskites still remains a challenge, yet to overcome.
Herein, we report stable p-type polymer as effective hole transport layer sandwiched between perovskite thin film and top electrode. In this work we have optimized the device structure by studying the perovskite film morphology with varying annealing time, varying polymer concentration and hole transport layer thickness. Surface modification of electron selective metal oxide thin films in organic solar cells for enhanced efficiency and stability Canceled Paper Author s : Show Abstract.
In this work enhanced lifetime and performance of organic solar cells is reported by using a surface modified metal oxide cathode interlayer. Enhanced lifetime is attributed to passivation of metal oxide surfaces from atmospheric oxidation. Oxidation of bare metal oxide interface can lead to traps which enhance recombination at organic-inorganic interface. Electron selective interfaces with and without modification are analyzed vs.
Inkjet printing of organic photovoltaics using a water-based active layer ink Paper Author s : Show Abstract. Chlorinated and Aromatic solvents typically used for the processing of Organic Photovoltaics, may not be used in large scale manufacturing of OPVs as they pose serious risks towards human health and the environment. Thus there is a need to develop a medium by which the OPV materials may be processed safely. We successfully inkjet printed working proof-of-concept devices using this water based ink. Efficient vacuum-deposited tandem organic solar cells with fill factor higher than single junction subcells Paper Author s : Show Abstract.
We report efficient vacuum-deposited tandem organic photovoltaics comprising of fullerenes as acceptors and two complementary absorbing donors, 2- 2- 5- 4- diphenylamino phenyl thieno[3,2-b]thiophenyl thiazolyl methylene malononitrile DTTz and 2- 7- 5- dip-tolylamino thiophenyl benzo[c]-[1,2,5]thiadiazolyl methylene malononitrile DTDCTB. The p-doped layer enables increasing the short circuit current density by tuning relative positions of sub-cells in the devices to have maximum optical field.
Moreover, the introduction of TAPC:MoO3 benefits to the higher fill factor without losing voltage even with the thick active layers. As a result, TOPV with a power conversion efficiency up to 9. Application of metal nanoparticle-conducting polymer composite to organic based solar cells Paper Author s : Show Abstract. Recently, organic based solar cells, such as organic solar cells OSCs and dye-sensitized solar cells DSSCs , have attracted considerable attention due to their unique advantages including low cost, solution processability, and mechanical flexibility.
Dye anchoring functional groups on performance of dye sensitized solar cells: Comparison between alkoxysilyl and carboxyl groups Paper Author s : Show Abstract. Two dye anchoring functional groups, alkoxysilyl and carboxyl groups, were compared to investigate their influence on the performance of dye sensitized solar cells.
Dimethylaminoazobenzene was selected as a chromophore. The difference was observed on improvement of an open circuit photovoltage by 60 mV and on the lifetimes of an electron in the TiO2 conduction band for the dye with the alkoxysilyl functional group compared to the carboxyl group, suggesting that an alkoxysilyl functional group is more attractive to retard the charge recombination reaction between an electron in the TiO2 conduction band and an oxidized form of an electrolyte redox couple.
High-performance planar-heterojunction perovskite solar cell using surface modified hole-transport layer Paper Author s : Show Abstract. Harnessing atomic layer deposition to directly map the morphology of organic photovoltaic bulk heterojunctions Paper Author s : Show Abstract. Investigating the morphology of OPV BHJ is extremely challenging, as no direct high-resolution characterization methods are available for such systems.
We show that atomic layer deposition ALD , a conventional thin-film processing technique, can be used as a characterization tool to directly map the morphology of OPV BHJs. ALD is commonly used for producing conformal coatings on top of a given substrate. However, when applying metal-oxide ALD onto organic materials with no surface reactivity, the precursors diffuse into the organic film and generate a sub-surface deposition of the metal oxide. This study demonstrates a new, alternative and general method for the visual characterization of organic functional blends.
Tuesday 11 August Show All Abstracts. Kafafi , Lehigh Univ. United States Plenary Session Details. Simultaneously, even when there is a small overlap between the two wavefunctions, we can successfully keep rather high radiative decay rate kr by inducing a large oscillator strength f. In this talk, we review material design, synthesis, photophysics and OLED performance and discuss the future prospects.
I will present examples of organic electrodes, transistors and other devices for recording and stimulation of brain activity and discuss how they can improve our understanding of brain physiology and pathology, and how they can be used to deliver new therapies. Ultraflexible organic thin-film devices for wearable and implantable electronics Plenary Presentation Paper Author s : Show Abstract.
Mechanically flexible and stretchable devices are expected to open new possibilities in fields of wearable and implantable electronics. From this viewpoint, ultraflexible organic thin-film devices, such as organic thin-film transistors OTFTs , organic photovoltaic cells OPVs , and organic light-emitting diodes OLEDs , have attracted much attention recently. We will also describe emerging applications using ultraflexible and stretchable electronic systems in the fields of biomedical electronics.
Recent progress on hybrid organic-inorganic and perovskite-based solar cells Plenary Presentation Paper Author s : Show Abstract. By combining the attributes from both organic and inorganic species, the light-harvesting hybrid perovskite e. CH3NH3PbI3 materials possess amazing physical properties that led to high performance solar cells within only a few years of research.
Film formation and interface engineering of perovskite materials are crucial parameters that determine the resulting solar cell efficiency. Besides single junction perovskite-based solar cells, research has turned to the tandem devices that combine another low band gap material such as Si in order to achieve even higher efficiency. My presentation will summarize recent progress in this field and report on new results from UCLA e. Session 1: Organic Photovoltaics Keynote Session. To live and let die: the role of excitons in the life of organic devices Keynote Presentation Paper Author s : Show Abstract.
Poly sulfobetaine methacrylate s as electrode modifiers for inverted solar cells Presentation Recording Invited Paper Paper Author s : Show Abstract. We demonstrate the use of polymeric zwitterions, namely, poly sulfobetaine methacrylate PSBMA , as solution-processable work function reducers for inverted organic electronic devices.
A notable feature of PSBMA is orthogonal solubility relative to solvents typically employed in the processing of organic semiconductors. A strong permanent dipole moment on the sulfobetaine moiety was calculated by density functional theory. This work makes available a new class of dipole-rich, counterion-free, pH insensitive interlayers for use as strong work function reducers for any electrode.
Our recent work with PBDTTPD and wide-bandgap analogs sheds light on several structural parameters that critically impact polymer performance e. In parallel, our recent developments show that PBDTTPD and wide-bandgap analogs are some of the most promising systems for use in the high-band-gap cell of tandem and triple-junction solar cells. High-efficiency wide band-gap polymers are required in order to continue improving upon currently reported PCEs.
Aggregation and morphology control enables polymer solar cells with efficiencies near This results in a well-controlled and near-ideal polymer:fullerene morphology containing highly crystalline yet small polymer domains that is controlled by polymer aggregation during warm casting and thus insensitive to the choice of fullerenes.
Organic solar cell
Ultra-sonic spray-coating is a scalable manufacturing technique for thin-film electronics, as it permits smooth-films to be fabricated at high speed over large areas. We demonstrate that air-based coating-processes are compatible with conjugated-polymer optoelectronics, and shown that carbazole based co-polymers can be processed in into organic photovoltaic devices OPV under ambient conditions without any apparent loss in device efficiency.
Activating grain boundaries for high-performance hybrid perovskite solar cells Paper Author s : Show Abstract. Grain boundaries GBs in the crystal structure detrimentally decrease power conversion efficiency PCE in hybrid perovskite solar cells, where defects, traps as well as energetic disorder cause significant non-radiative recombination energy loss. In this talk, we will show that the GBs can be activated as active carrier collection channels for increased carrier collection efficiency.
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Space-charge-regions between each grain can suppress non-radiative recombination and enhance carrier collection efficiency. Additive controlled solution process for high efficiency perovskite solar cells Invited Paper Paper Author s : Show Abstract. Controlling the morphology and composition of the perovskite layer has been found critical for developing high-performance perovskite solar cells.
Here we demonstrate that the use of chemical additive e. For one-step deposition, additive-assisted thermal decomposition of precursor films leads to the formation of perovskite films with good surface coverage. The thermal decomposition process is also beneficial for accelerating PbI2-to-perovskite conversion for sequential deposition. Perovskite thin film formation during solution processing: an in situ time-resolved multiprobe investigation Invited Paper Paper Author s : Show Abstract.
Wednesday 12 August Show All Abstracts. Sub-ns triplet state formation in polymer: fullerene photovoltaic blends Invited Paper Paper Author s : Show Abstract. I will present recent results on charge generation, recombination, and triplet state formation in various bulk heterojunction photovoltaic blends investigated by femto- to microsecond broadband Vis-NIR transient absorption TA pump-probe spectroscopy.
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Specifically, we looked into the processes following exciton dissociation in low-bandgap polymer and small molecule solar cells using either fullerene or non-fullerene acceptors. The effect of 2D-Langevin and trap-assisted recombination on the open circuit voltage in organic solar cells Paper Author s : Show Abstract. We have clarified the impact of trapping on the recombination dynamics in polymer:fullerene blends using the bulk heterojunction blend poly[2,5-bis 3-tetradecylthiophenyl thieno[3,2-b]thiophene] and [6,6]-phenyl-Cbutyric acid methyl ester at different weight ratios as a model system.
Results show that both the decay of photo generated charge and the light ideality factor at a polymer:fullerene weight ratio of are fully consistent with 2-dimensional Langevin recombination, in the case the recombination is seen to be affected by electron trapping.
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The theory of 2-dimensional Langevin recombination is extended to the case with high trap density in agreement with the observations in the case. Manipulation of the dielectric constant of non-fullerene organic semiconductors Invited Paper Paper Author s : Show Abstract. Si: Thus, homojunction organic diodes tend to have low efficiency as neither thermal activation nor external electric field are sufficient to efficiently overcome the strong Coulombic interaction of the excitons.
In this presentation we discuss how non-fullerene acceptors can be engineered to give high film dielectric constants and how the dielectric constant affects the optoelectronic properties. Exciton binding energy limitations in organic materials and potentials for improvements Presentation Recording Paper Author s : Show Abstract. In current organic photovoltaic devices, the loss in energy caused by the inevitable charge transfer step leads to a low open circuit voltage. A possible approach to avoid these losses is to tune the exciton binding energy below 25 meV, which would increase the power conversion efficiency towards the Shockley Queisser limit for inorganic solar cells.
We discuss the limit of currently used organic materials and propose potential ways to increase the ionic and electronic part of the dielectric function in order to further lower the limit of the exciton binding energy in organic materials. Conditions for charge transport without recombination in low mobility organic solar cells and photodiodes Presentation Recording Paper Author s : Show Abstract. Charge transport in organic solar cells is usually characterized by the mobility-lifetime product. Using newly developed experimental techniques we show that the onset of the efficiency limiting photocarrier recombination is determined by the charge that can be stored on the electrodes.
Based upon this physics we propose the mobility-recombination coefficient product as more convenient figure of merit to minimize the recombination losses. The findings allow us to determine the charge collection and generation efficiencies in fully operational devices and are therefore relevant to a wide range of light harvesting systems. Session 4: Applications of Nanophotonics.
This talk will describe an approach to create architecturally compatible and decorative thin-film-based hybrid photovoltaics. Most current solar panels are fabricated via complex processes using expensive semiconductor materials, and they are rigid and heavy with a dull, black appearance.