Perovskite based solar cells, mostly employ solution processed perovskite layers. Evaporated methylammonium lead iodide perovskite layers have also been reported and been employed in solar cells. Our group has developed several perovskite based solar cells, using vacuum based perovskite preparation methods. These metal oxide free p-i-n type perovskite cells exhibit high power-conversion efficiencies. We have extended this work to fully evaporated perovskite devices reaching power conversion efficiencies as high as 20 % in a planar single junction device and similar performance in tandem devices. Avenues to further increase the device performance by using multiple cation perovskite prepared via sublimation will also be presented.

Three-dimensional (3D) methylammonium lead iodide perovskite solar cells are undoubtedly leading the photovoltaic scene with their power conversion efficiency (PCE) >23%, holding the promise to be the near future solution to harness solar energy. Tuning the material composition, i.e. by cations and anions substitution, and functionalization of the device interfaces have been the successful routes for a real breakthrough in the device performances. However, poor stability (= device lifetime), mainly due to material decomposition upon contact with water, is now the bottleneck for the widespread of this technology. Diverse technological approaches have been proposed delivering appreciable

Solution-processed materials have significant promise for future generation solar cells. We will discuss our efforts to understand charge transport and carrier lifetimes as a function of structure in two classes of materials for thin film solar cells – organic semiconductors and hybrid organic metal halides. Organic bulk heterojunction (BHJ) solar cells have a complex structure where an electron donor and acceptor meet in a bicontinuous network with nanoscale dimensions. The development of non-fullerene acceptors has led to prospects for improvement of their power conversion efficiency through reduced losses in the open circuit voltage. We will discuss recent work to understand the origin of these effects in non-fullerene acceptors. Hybrid organic metal halides, such as CH3NH3PbI3, have garnered significant attention because they are earth-abundant, solution-processable materials that can be used to form solar cells with high power conversion efficiency (>20%). An interesting feature of these compounds is the ability to form layered Ruddlesden-Popper phases with quantum confinement by judicious choice of mixed organic cations. We will present our work on understanding the electronic properties of 3D and 2D organic metal halides using Pb- and Bi-based systems using techniques such as time-resolved microwave conductivity. We will also describe our efforts to characterize and control the phase behavior in thin films of layered Ruddlesden-Popper compounds, (CH3(CH2)3NH3)2(CH3NH3)n−1PbnI3n+1 (n = 1, 2, 3, 4) towards high stability devices. Despite structural disorder apparent from quantitative analysis of grazing incidence X-ray scattering and electron microscopy, these materials surprisingly still have sharp band edges. The implications of these studies suggest that there is still much to be learned from these exciting materials systems.

Metal‐halide perovskite materials have achieved tremendous progress in recent years due to their excellent optical and electrical properties. Moreover, their facile, low‐cost fabrication, and deposition processes seem to be a match extracted from a science fiction movie, promising a great future with applications beyond research laboratories premises. This is particularly true for solar energy harvesting devices, the metal halide perovskite solar cells (PSCs), which were considered in 2013 as one of the top ten scientific breakthroughs. PSCs certified power conversion efficiency (PCE) has progressed from 3.9% in 20091 to 22.7% in 2018 mainly as a result of the intense global research effort.

Meeting Point: Bldg 5, Room 3202.

2:30 PM: Yuliar Firdaus (KAUST), "Practical Efficiency Limits in Single- and Multi-Junction Nonfullerene Bulk Heterojunction Solar Cells"

2:45 PM: Sanaa Alshammari (KAUST), "Development of multilayer metal oxide electron transport interlayers for organic photovoltaics"

3:00 PM: Maria Bidikoudi (Technological Educational Institute of Crete), "Device Engineering for High Efficiency Inverted Perovskite Solar Cells"

In a molecular photovoltaic device, charge separation and energy conversion result from the evolution of a photogenerated exciton into a charge separated state, in competition with recombination to ground. The efficiency of charge separation is a function of the molecular packing and energy level alignment near the interface, and of disorder in these properties. Understanding the effect of structure, energetics and disorder on the competition between charge separation and recombination helps to identify the factors controlling device photovoltage and ultimately conversion efficiency. Here, we address the factors controlling generation efficiency and photovoltage in molecular donor: acceptor solar cells using a combination of electrical and spectroscopic measurements and numerical models. We explore the limits to Voc using a model of non-radiative recombination, and demonstrate how choice of materials and control of processing may influence voltage losses. We use these results to consider the importance of chemical structure, the phase behaviour and microstructure of the binary system in controlling actual performance and the ultimate limitations placed on solar to electric conversion by the molecular nature of the materials. We also address methods for the experimental determination of non-radiative recombination rates.

In this talk I will first describe a novel methodology for the fast evaluation of donor/acceptor systems for photovoltaics. The new approach, up to 100 times faster than conventional optimization protocols, is based on the use of Raman to quantify the local thickness and composition in samples with lateral gradients on parameters of interest. Raman images are combined with photocurrent images (LBIC) to identify the optimum conditions. We demonstrate the potential of the methodology optimizing three systems PCDTBT:PC70BM, PTB7-Th:PC70BM and PffBT4T-2OD:PC70BM, obtaining efficiencies circa 6%, 8% and 10%, respectively, using less than 50 mg of each polymer in the process. I will show that this method can be used also to analyze blends containing non-fullerene acceptors and ternary systems and it can be extended for the case of evaporated bilayer solar cells by using moving shadow masks as well as polymer:polymer processed through microfluidic chips dispensers. Finally, I will describe our first attempts to use these large datasets (>25.000 points per material system) as input in machine learning algorithms and what we could learn from this exercise.

Electrodes with sufficiently high, or low, work functions to match the appropriate band edge of the semiconductor are required in all high performance devices for efficient injection (and/or extraction) of holes, or electrons, respectively. Ambient processability will confer an added design and manufacturing advantage. In this talk, I will report our materials development to make ambient processable shallow (≤4.0 eV) and deep (≥5.8 eV) charge injection and extraction layers. For ultra-high work function interlayer, I will discuss self-compensated doped polymers which are generated by a separate charge-carrier doping of conjugated polyelectrolytes and compensation by their covalently bonded counter-ion, which enables the use of strong dopants to access extreme workfunction. This strategy also stabilize film from de-doping and suppress dopant migration. I will further discuss the role of these counter-ion and also the spectator cations in their solution-processability, bulk and interface morphologies in workfunction manipulation. For ultra-low work function interlayer, I will discuss using di- and higher-valent anions with negative gas-phase electron detachment energies, such as oxalate, sulfite, carbonate, sulfate and phosphate. Their electron donor level can remain sufficiently shallow in disordered matrices, particularly upon loss of the stabilizing hydration water, to provide spontaneous doping of the semiconductor, especially in the presence of holes injected by the opposite contact.

Seaside atrium of University Library

This talk will provide thoughts from the perspective of a materials science company about some technical challenges related to the development of more efficient conventional solar modules. The discussion will highlight expected trends related to cell devices (with a brief illustration of recent materials-based activities related to metallization of n-type wafers) and modules (with discussion of ongoing development of backsheets for bifacial modules). Novel materials and devices must last for at least 30 years, which is a particular challenge in the hot and arid climate of the Middle East region. As a result, this talk will include thoughts about the challenges of validating the durability of new technologies and suggestions related to accelerated testing methods.

The increasing energy demands of the world’s population and the quickly diminishing fossil fuel reserves together suggest the urgent need to secure long-lasting alternative and renewable energy resources. Infrared (IR) energy harvesting from waste heat can be a promising contribution for sustainable energy in addition to harvesting from the visible light spectrum. Here, we present a plasmonic rectenna (antenna integrated with a rectifier) for harvesting energy from the Tera hertz (IR) spectrum. The implementation of rectennas for energy harvesting at such high frequencies has remained an elusive research area due to the limitations of nano-scale fabrication and the inability to implement rectifiers that could handle electromagnetic (EM) radiations oscillating at trillion times per second. In this work, a resonant bowtie nano-antenna has been optimized to produce highly enhanced localized fields at the bow tip. The phenomena of plasmon oscillation and hot spot creation at the feed point of the nano-antenna as a result of incident IR energy have been studied through EM simulations and Electron Energy Loss Spectroscopy (EELS). For the rectifier to function at such high frequencies, Metal-Insulator-Metal (MIM) diode has been realized because of its fast response time. The rectenna prototype demonstrates decent zero bias responsivity at a relatively lower dynamic resistance. Optical testing confirms that the device is capable of collecting and rectifying energy at 28.3 THz (10.6 um), albeit with poor efficiency. Numerous challenges in this area and the ways to move forward will also be discussed in this talk.

CSEM Brasil has developed the largest roll to roll printing line worldwide dedicated to OPV and has successfully spun-out SUNEW, the company that is bringing to market industrial scale OPV, breaking successive records in terms of production output and commercial installations globally. This talk will share some of Tiago´s insights along the journey, the main technological challenges as well as the reasons why he believes OPV will have a big impact on the cities, vehicles and buildings of the future.

A big challenge for Organic PhotoVoltaic (OPV) production is to succeed in the industrial scale-up, from lab < 0,1cm² cells to Roll to roll > 100cm² modules. OPV materials and performances have seen huge progress over the past 2 years, related to the breakthrough of non-fullerene acceptors and new high-performance donor polymers. Today, academic researchers publish efficiency for lab devices over 17%. But these performances are achieved in very specific environmental and processing conditions, and for extremely small areas of OPV cells One of the biggest challenge for OPV industrials today is to succeed in transferring these materials from lab cell to industrial modules, and limiting the efficiency losses linked to the scale-up. In Armor production lines, we observe a loss of around 50% from lab cells efficiency to stabilized commercial module efficiency. I will present the analysis of the origin of these impressive losses in performances for different OPV structures, based on fullerene and non-fullerene acceptors. The impact of environment, such as oxygen, light or humidity will be assessed, as well as the influence of processing conditions. We will see that an annealing step under Nitrogen can boost OPV performances for some materials, whereas the same annealing step in air completely deteriorates cells efficiency. Relative humidity in the coating room can have major impact on ETL roughness and cause direct performance decrease over time. Roots of degradation of performances form lab to fab, impact of environmental and processing conditions on performances and stability at module scale, and effects of the cell size and interconnects will be presented. Ways for improvements and associated characterization means and techniques will be addressed.

11:30 AM: Jan Kosco(KAUST), "Residual Pd in Conjugated Polymers and its Impact on Photocatalytic Hydrogen Evolution"

11:45 AM: Alexandra Paterson(KAUST), "Non-Fullerene Acceptor O-IDTBR Organic Field-Effect Transistors with Electron Mobility > 1 cm2/Vs“

12:00 PM: Muna Khushaim(Taibah Univesity), "Touching Atoms by using Atom Probe Tomography"

The solar photovoltaic (PV) market has experienced an accelerated growth, accompanied by remarkable cost declines for solar PV technologies. The levelized cost of electricity (LCOE) from solar photovoltaics decreased by 69% between 2010 and 2016 – coming well into the cost range of fossil fuels. Photovoltaic technology still has plenty of room for innovation and thus, cost reduction. New technologies, materials and highly productive manufacturing equipment are continually improved in order to reduce production costs and increase cell and module efficiencies at the same time. This presentation will discuss new developments that support the progress in crystalline silicon PV production by identifying manufacturing and technology issues and trends for wafer, cell and module production in particular. Definitely, Photovoltaics has a bright future, and its technological development is the key to success.

HAALA Energy is a Saudi solar PV project developer and EPC with offices in KAUST and Jeddah. The firm specializes in distributed commercial-scale solar PV, and develops peak-shaving and hybrid solutions to help commercial, industrial and agricultural clients reduce their energy costs and mitigate fuel price risk. HAALA Energy sees itself as a new breed of solar developer; with an approach that combines deep local market understanding with a rigorous and analytical approach to project development and a business model that promotes employee ownership.

Iyris is a KAUST Solar Center spin-out formed in 2018 seeking to develop transparent photovoltaics for buildings and greenhouses as well as their corresponding systems. In this talk, we will outline some of the ‘balance-of-systems’ design considerations which are somewhat unique to the building-integrated nature of our solar panels: An example being cost-effective, per-panel maximum power point tracking to harvest the greatest amount of solar energy available.

In addition, we will discuss some of the hidden benefits to our transparent photovoltaic technology, including a significant reduction in heat transmission through the solar panel. In high irradiance and hot climates such as Saudi Arabia, this heat reduction significantly contributes to the value proposition of Iyris photovoltaic windows.

The technology at the core of NOMADD was developed at KAUST. It is now deployed on a variety of commercial projects across the region, including the upcoming 16MW Dubai reservoir project, the world's largest rooftop. Nomadd recently secured series B investment from a local manufacturing partner in Jeddah. NOMADD is now scaling deployment sizes, product portfolio and team.

Halide perovskites are currently of intense interest for solar energy and optoelectronic applications. Remarkable gains in performance have been demonstrated in the past few years. However, most current devices are still limited by non-radiative recombination losses. We focus on uncovering and eliminating these loss processes. Experiments suggest that electrical heterogeneities in both the perovskite active layer, as well as the perovskite/electrode interface affect carrier diffusion and non-radiative recombination processes. Both optical and scanning probe microscopy experiments show how grain boundaries slow lateral carrier transport and how interfaces serve as recombination centers in these systems. Multimodal microscopy experiments reveal the combined role of electrochemistry and ion motion on defect formation. We show that by using chemical passivation of the perovskite surfaces we are able to obtain carrier lifetimes and photoluminescence intensities in solution-processed thin films that rival those in the best single crystals, achieving over 90% PL internal quantum efficiency and quasi-Fermi level splittings that exceed approach the Shockley-Queisser limit under illumination. We further explore the defect chemistry on local ion motion and phase stability of mixed perovskites.

Thanks to the intensive research efforts of a large scientific community over the past 7 years, lead (Pb)-based hybrid perovskite solar cells have reached impressive power conversion efficiency. Against the initial criticism about their instability, also large improvements in the thermal and photo stability of this kind of solar cell were obtained by using more stable precursors, and robust hole/electron transport layers. Despite these outstanding accomplishments, the toxicity of lead causes concerns about the possible large-scale utilization of this new type of solar cell. Among the various alternatives to lead, Sn has been recognized to have a great potential, as the Sn-based hybrid perovskites display excellent optical and electrical properties such as high absorption coefficients, very small exciton binding energies and high charge carrier mobilities. In my talk I will show that Sn-based perovskites display evidences of photoluminescence from hot-carriers with unexpectedly long lifetime. The asymmetry of the PL spectrum at the high-energy edge, is accompanied by the unusually large blue shift of the time-integrated photoluminescence with increasing the excitation power. These phenomena are associated with slow hot carrier relaxation and state-filling of band edge states. I will further show all-tin-based hybrid perovskite solar cells with efficiencies of up to 9%. This record result is obtained with the addition of trace amount of 2D tin perovskite, which initiates the homogenous growth of highly crystalline and oriented FASnI3 grains at low temperature.

An ever increasing interest in the development and application of innovative optical and optoelectronic devices places greater emphasis for the advancement of new smart and functional materials that are readily processable. Significant progress has already been realized in the fields of organic light-emitting diodes (OLEDs) and photovoltaic cells (OPVs) through development of novel semiconducting materials. Here we discuss developments and advancements in materials design towards photonic structures that aid and improve light management in organic and inorganic/organic hybrid devices, with focus on solar cells. We cover systems targeted for use in light in-coupling structures, anti-reflection coatings, and beyond. Extension to architectures for heat management, important for a broad range of photovoltaic device platforms, including inorganic, inorganic/organic hybrid and organic devices, will also be presented.

Perovskites have emerged as low-cost, high efficiency photovoltaics with certified efficiencies of 22.1% approaching already established technologies. The perovskites used for solar cells have an ABX3 structure where the cation A is methylammonium (MA), formamidinium (FA), or cesium (Cs); the metal B is Pb or Sn; and the halide X is Cl, Br or I. Unfortunately, single-cation perovskites often suffer from phase, temperature or humidity instabilities. This is particularly noteworthy for CsPbX3 and FAPbX3 which are stable at room temperature as a photoinactive “yellow phase” instead of the more desired photoactive “black phase” that is only stable at higher temperatures. Moreover, apart from phase stability, operating perovskite solar cells (PSCs) at elevated temperatures (of 85 °C) is required for passing industrial norms.

In the area opposite of the Grand Mosque (near the wooden bridge).