The Influence of Substituent Orientation on the Photovoltaic Performance of Phthalocyanine-Sensitized Solar Cells

This is the peer reviewed version of the following article:Chemistry - A European Journal 22.13 (2016): 4369-4373, which has been published in final form at http://dx.doi.org/10.1002/chem.201600166. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-ArchivingPhthalocyanines (Pcs) are used as sensitizers in dye-sensitized solar cells (DSSCs) because of their stability and intense absorption in the red and near-IR regions. Impressive progress has been made in photovoltaic efficiencies by introduction of bulky peripheral substituents to help suppress macrocycle aggregation. To reach benchmark efficiencies reported for other related dyes, new designs need to be explored. Single carboxy-ZnPc regioisomers substituted at the non-peripheral positions by rigid aryl groups have now been studied, which has shed light on the influence of steric hindrance and/or orientation of the substituent around the anchoring group on the photovoltaic response. The regioisomer bearing the aryl group far away from the anchoring group produces a more effective sensitization of the TiO2 films and higher short-circuit photocurrent density (Jsc). Taking advantage of the good photovoltaic performance in the near-IR region of this ZnPc, it was combined with another appropriate dye for panchromatic sensitization of the mesoporous photoelectrode and an increase of the overall device efficiencyFinancial support from the European Union (FP7-ENERGY-2012- 1 framework, GLOBASOL project, Proposal No 309194-2), from the Spanish MINECO (CTQ2014-52869-P), Comunidad de Madrid (FOTOCARBON S2013/MIT-2841), and MECD (F.P.U. fellowship to L.T.) is gratefully acknowledge

Low temperature dye-sensitized solar cells based on conformal thin zinc oxide overlayer on mesoporous insulating template by atomic layer deposition

Low temperature processing of dye-sensitized solar cells (DSCs) is essential to enable commercialization with low cost plastic substrates and diminish the overall manufacturing cost.We report a low temperature processing route for photoanodes where thin ZnO nanoshell is deposited by atomic layer deposition at 150°C, on a mesoporous insulating template. We found that a 6 nm ZnO overlayer on a 3 μm mesoporous nanoparticle Al2O3 template shows a power conversion efficiency of 4.2 % with the standard organic sensitizer (coded Y123) and cobalt bipyridine redox mediator

AI Potentiality and Awareness: A Position Paper from the Perspective of Human-AI Teaming in Cybersecurity

This position paper explores the broad landscape of AI potentiality in the context of cybersecurity, with a particular emphasis on its possible risk factors with awareness, which can be managed by incorporating human experts in the loop, i.e., "Human-AI" teaming. As artificial intelligence (AI) technologies advance, they will provide unparalleled opportunities for attack identification, incident response, and recovery. However, the successful deployment of AI into cybersecurity measures necessitates an in-depth understanding of its capabilities, challenges, and ethical and legal implications to handle associated risk factors in real-world application areas. Towards this, we emphasize the importance of a balanced approach that incorporates AI's computational power with human expertise. AI systems may proactively discover vulnerabilities and detect anomalies through pattern recognition, and predictive modeling, significantly enhancing speed and accuracy. Human experts can explain AI-generated decisions to stakeholders, regulators, and end-users in critical situations, ensuring responsibility and accountability, which helps establish trust in AI-driven security solutions. Therefore, in this position paper, we argue that human-AI teaming is worthwhile in cybersecurity, in which human expertise such as intuition, critical thinking, or contextual understanding is combined with AI's computational power to improve overall cyber defenses.Comment: 10 pages, Springe

Time-dependent density functional theory study of squaraine dye-sensitized solar cells

n/

Phthalocyanines and Porphyrinoid Analogues as Hole-and Electron-Transporting Materials for Perovskite Solar Cells

Organic–inorganic lead halide perovskite absorbers in combination with electron and hole transporting selective contacts result in power conversion efficiencies of over 23% under AM 1.5 sun conditions. The advantage of perovskite solar cells is their simple fabrication through solution-processing methods either in n-i-p or p-i-n configurations. Using TiO2 or SnO2 as an electron transporting layer, a compositionally engineered perovskite as an absorber layer, and Spiro-OMeTAD as a HTM, several groups have reported over 20% efficiency. Though perovskite solar cells reached comparable efficiency to that of crystalline silicon ones, their stability remains a bottleneck for commercialization partly due to the use of doped Spiro-OMeTAD. Several organic and inorganic hole transporting materials have been explored to increase the stability and power conversion efficiency of perovskite solar cells. IIn this review, we analyse the stability and efficiency of perovskite solar cells incorporating phthalocyanine and porphyrin macrocycles as hole- and electron transporting materials. The π–π stacking orientation of these macrocycles on the perovskite surface is important in facilitating a vertical charge transport, resulting in high power conversion efficiencyWe are grateful for the financial support of the MINECO, Spain (CTQ2017-85393-P) and the Comunidad de Madrid (FOTOCARBON, S2013/MIT-2841). IMDEA Nanociencia acknowledges support from the ‘Severo Ochoa’ Programme for Centres of Excellence in R&D (MINECO, Grant SEV-2016-0686). MKN thanks the EPFL and the Swiss National Science Foundatio

Ionic polarization-induced current-voltage hysteresis in ch3nh3pbx3 perovskite solar cells

CH3NH3PbX3 (MAPbX3) perovskites have attracted considerable attention as absorber materials for solar light harvesting, reaching solar to power conversion efficiencies above 20%. In spite of the rapid evolution of the efficiencies, the understanding of basic properties of these semiconductors is still ongoing. One phenomenon with so far unclear origin is the so-called hysteresis in the current–voltage characteristics of these solar cells. Here we investigate the origin of this phenomenon with a combined experimental and computational approach. Experimentally the activation energy for the hysteretic process is determined and compared with the computational results. First-principles simulations show that the timescale for MAþ rotation excludes a MA-related ferroelectric effect as possible origin for the observed hysteresis. On the other hand, the computationally determined activation energies for halide ion (vacancy) migration are in excellent agreement with the experimentally determined values, suggesting that the migration of this species causes the observed hysteretic behaviour of these solar cells

Efficient and Stable Perovskite Solar Cells by Tailoring of Interfaces

The interface tailoring is crucial for the efficiency and stability of Perovskite Solar Cells (PSCs). The reported interface engineering primarily focuses on the energy level turning and trap state passivation to improve the photovoltaic performance of PSCs. In this review, molecule modifications are classified according to the basics of electron transfer mechanisms for the interface tailoring of materials. An in‐depth analysis of energy level modification and trap passivation, as well as the universal Density Functional Theory (DFT) method employed in interface tailoring. In addition, strategies to address environmental protection and large‐scale mini‐modules fabrication by interface engineering are also discussed. This review can guide the researchers in understanding interface engineering to design interface materials for efficient, stable, and eco‐friendly PSCs