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This document is the Accepted Manuscript version of a Published Work that appeared in final form in The journal of physical chemistry letters, copyright © 2023 The Authors. Published by American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/full/10.1021/acs.jpclett.3c00643, Poly(amidoamine) (PAMAM) dendrimers are used to modify the interface of metal-semiconductor junctions. The large number of protonated amines contributes to the formation of a dipole layer, which finally serves to form electron-selective contacts in silicon heterojunction solar cells. By modification of the work function of the contacts, the addition of the PAMAM dendrimer interlayer quenches Fermi level pinning, thus creating an ohmic contact between the metal and the semiconductor. This is supported by the observation of a low contact resistivity of 4.5 mO cm2 , the shift in work function, and the n-type behavior of PAMAM dendrimer films on the surface of crystalline silicon. A silicon heterojunction solar cell containing the PAMAM dendrimer interlayer is presented, which achieved a power conversion efficiency of 14.5%, an increase of 8.3% over the reference device without the dipole interlayer., This research has been supported by the Spanish government through Grants PID2019-109215RB-C41, PID2019- 109215RB-C43, and PID2020-116719RB-C41 funded by MCIN/AEI/10.13039/501100011033. Thomas Tom acknowledges the support of the Secretaria d’Universitats i Recerca de la Generalitat de Catalunya and the European Social Fund (2019 FI_B 00456). In addition, the authors thank the technical staff from Barcelona Research Center in Multiscale Science and Engineering from the Universitat Politecnica ̀ de Catalunya for their expertise and helpful discussions over the XPS results, Dr. Oriol Arteaga from the Universitat de Barcelona for the ellipsometry measurements, and Guillaume Sauthier from the Catalan Institute of Nanoscience and Nanotechnology for his contribution to UPS measurements and their discussion., Peer Reviewed, Postprint (published version)

High open-circuit voltage in Sb2Se3 thin-film solar cells is a key challenge in the development of earth-abundant photovoltaic devices. CdS selective layers have been used as the standard electron contact in this technology. Long-term scalability issues due to cadmium toxicity and environmental impact are of great concern. In this study, we propose a ZnO-based buffer layer with a polymer-film-modified top interface to replace CdS in Sb2Se3 photovoltaic devices. The branched polyethylenimine layer at the ZnO and transparent electrode interface enhanced the performance of Sb2Se3 solar cells. An important increase in open-circuit voltage from 243 mV to 344 mV and a maximum efficiency of 2.4% was achieved. This study attempts to establish a relation between the use of conjugated polyelectrolyte thin films in chalcogenide photovoltaics and the resulting device improvements., This research was supported by the Spanish government through grants PID2019-109215RB-C41, PID2019-109215RB-C43, and PID2020-116719RB-C41 funded by MCIN/AEI/10.13039/501100011033. This research was funded by the European Union H2020 Framework Programme under Grant Agreement No. 866018, low-dimensional semiconductors for optically tunable solar harvesters (SENSATE). E.S. acknowledges the ICREA Academia program. One of the authors (T.T.) acknowledges the support of the Secretaria d’Universitats i Recerca de la Generalitat de Catalunya and European Social Fund (2019 FI_B 00456)., Peer Reviewed, Postprint (published version)

This is the peer reviewed version of the following article: Tom, T. [et al.]. Deoxyribonucleic acid-based electron selective contact for crystalline silicon solar cells. "Advanced materials technologies (Weinheim)" [en línia], 10 Febrer 2023, [Consulta: 12 Desembre 2022]. Disponible a: http://hdl.handle.net/2117/377832, which has been published in final form at https://onlinelibrary.wiley.com/doi/10.1002/admt.202200936. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited., Development of carrier selective contacts for crystalline silicon solar cells has been recently of great interest toward the further expansion of silicon photovoltaics. The use of new electron and hole selective layers has opened an array of possibilities due to the low-cost processing and non-doping contacts. Here, a non-doped heterojunction silicon solar cell without the use of any intrinsic amorphous silicon is fabricated using Deoxyribonucleic acid (DNA) as the electron transport layer (ETL) and transition metal oxide V2O5 as the hole transport layer (HTL). The deposition and characterization of the DNA films on crystalline silicon have been studied, the films have shown a n-type behavior with a work function of 3.42 eV and a contact resistance of 28 mO cm2. This non-doped architecture has demonstrated a power conversion efficiency of 15.6%, which supposes an increase of more than 9% with respect to the cell not containing the biomolecule, thus paving the way for a future role of nucleic acids as ETLs., T.T. and E.R. shared co-first authorship. This research was supported by Spanish government through grants PID2019-109215RB-C41, PID2019-109215RB-C43, and PID2020-116719RB-C41 funded by MCIN/ AEI/10.13039/501100011033. One of the authors (T.T.) acknowledges the support of the Secretaria d’Universitats i Recerca de la Generalitat de Catalunya and European Social Fund (2019 FI_B 00456). Besides this, the authors thank technical staff from Barcelona Research Center in Multiscale Science and Engineering from Universitat Politècnica de Catalunya for its expertise and helpful discussions over XPS results, Dr. Oriol Arteaga Barriel from Universitat de Barcelona for the thickness measurements, and also Guillaume Sauthier from Catalan Institute of Nanoscience and Nanotechnology for his contribution through UPS measurements and discussions., Peer Reviewed, Postprint (published version)

In this work we study conjugated polyelectrolyte (CPE) films based on polyamidoamine (PAMAM) dendrimers of generations G1 and G3. These fractal macromolecules are compared to branched polyethylenimine (b-PEI) polymer using methanol as the solvent. All of these materials present a high density of amino groups, which protonated by methoxide counter-anions create strong dipolar interfaces. The vacuum level shift associated to these films on n-type silicon was 0.93 eV for b-PEI, 0.72 eV for PAMAM G1 and 1.07 eV for PAMAM G3. These surface potentials were enough to overcome Fermi level pinning, which is a typical limitation of aluminium contacts on n-type silicon. A specific contact resistance as low as 20 mO·cm2 was achieved with PAMAM G3, in agreement with the higher surface potential of this material. Good electron transport properties were also obtained for the other materials. Proof-of-concept silicon solar cells combining vanadium oxide as a hole-selective contact with these new electron transport layers have been fabricated and compared. The solar cell with PAMAM G3 surpassed 15% conversion efficiency with an overall increase of all the photovoltaic parameters. The performance of these devices correlates with compositional and nanostructural studies of the different CPE films. Particularly, a figure-of-merit (Vs) for CPE films that considers the number of protonated amino groups per macromolecule has been introduced. The fractal geometry of dendrimers leads to a geometric increase in the number of amino groups per generation. Thus, investigation of dendrimer macromolecules seems a very good strategy to design CPE films with enhanced charge-carrier selectivity., This research has received funding from the European Union H2020 Framework Programme under Grant Agreement no. 866018, Low dimensional semiconductors for optically tunable solar harvesters (SENSATE), by the Spanish Ministry of Science, Innovation and Universities under the MATERONE project (PID2020-116719RB-C41) as well as PID2019- 109215RB-C43 and PID2019-109215RB-C41. E.S. also thanks the ICREA Academia Program. One of the authors (T. Tom) acknowledges the support of the Secretaria d’Universitats i Recerca de la Generalitat de Catalunya and European Social Fund (2019 FI_B 00456). This work is also part of projects PID2020-115719RB-C21 (GETPV) and TED2021-131778B (TROPIC) funded b y MCIN/AEI/10.13039/ 5011000110033. Project TED2021-131778B (TROPIC) is also funded by European Union “NextGenerationEU”/PRTR.″, Peer Reviewed, Postprint (published version)

© 2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., This work studies the use of thin layers of polyethylenimine (PEI) as an interface film to produce electron selective contacts for photovoltaic applications in crystalline silicon. Generally, in conjugated polyelectrolytes such as PEI with a high Lewis basicity, charge is accumulated along the chain of the polymer and counter anions from the solvent create an intense dipole array. In this work, part of the amine groups in PEI are protonated by the solvent that behaves as a weak Bronsted acid during the process. The PEI band modification is able to eliminate Fermi level pinning at metal/semiconductor junctions as it shifts the work function of the metallic electrode by more than 1 eV. As a consequence, induced charge transport between the metal and the semiconductor forms an electron accumulation region and promotes enhanced selectivity., This research has been supported by Spanish government through Grants PID2019-109215RB-C41 (SCALED), PID2019-109215RB-C43, PID2020-116719RB-C41 (MATER ONE) and PID2020-115719RB-C21 (GETPV) and funded by MCIN/AEI/ 10.13039/501100011033. Besides this the work is also supported by the international Grants SENESCYT-2018 funded by Ecuadorian government., Peer Reviewed, Postprint (author's final draft)

This work studies the use of polymeric layers of polyethylenimine (PEI) as an interface modification of electron-selective contacts. A clearly enhanced electrical transport with lower contact resistance and significant surface passivation (about 3 ms) can be achieved with PEI modification. As for other conjugated polyelectrolytes, protonated groups of the polymer with their respective counter anions from the solvent create an intense dipole. In this work, part of the amine groups in PEI are protonated by ethanol that behaves as a weak Brønsted acid during the process. A comprehensive characterization including high-resolution compositional analysis confirms the formation of a dipolar interlayer. The PEI modification is able to eliminate completely Fermi-level pinning at metal/semiconductor junctions and shifts the work function of the metallic electrode by more than 1 eV. Induced charge transport between the metal and the semiconductor allows the formation of an electron accumulation region. Consequently, electron-selective contacts are clearly improved with a significant reduction of the specific contact resistance (less than 100 mO·cm2). Proof-of-concept dopant-free solar cells on silicon were fabricated to demonstrate the beneficial effect of PEI dipolar interlayers. Full dopant-free solar cells with conversion efficiencies of about 14% could be fabricated on flat wafers. The PEI modification also improved the performance of classical high-efficiency heterojunction solar cells., This research has been supported by the Spanish government through Grants PID2019-109215RB-C41, PID2019109215RB-C43, PID2020-115719RB-C21, and PID2020116719RB-C41 and funded by MCIN/AEI/10.13039/ 501100011033. Besides this the authors would like to thank Prof. Jordi LLorca for his expertise and helpful discussions of XPS results, as well as Dr. Rodrigo Fernández-Pacheco of the Laboratorio de Microscopias Avanzadas (LMA-INA) of Zaragoza for the HRTEM images and EDS and EELS analysis, and Guillaume Sauthier from ICN2 for his contribution through UPS measurements and discussions., Peer Reviewed, Postprint (published version)

Sputtered films of reduced molybdenum oxide (MoOx) with a molybdenum trioxide target in different pressures and atmospheres were deposited in varying temperatures. Compositional, optic, and electric characteristics of the samples were studied. X-ray photoelectron spectroscopy revealed reduced states when working in the hydrogen + argon atmosphere implying that stoichiometry could be controlled by adding some hydrogen in the sputtering chamber. The effect of slightly increasing the substrate temperature during deposition was also studied and lead to the presence of metastable Mo4+ states at 3 mTorr. Optical properties match the ones already in the literature, and transmittances of 90% were achieved. The results support sputtering as a viable method of depositing MoOx films apart from thermal evaporation for many applications., This research has been supported by the Spanish Ministerio de Economía, Industria y Competitividad (ENE2016-78933-C4-1-R and ENE2016-78933-C4-2-R), Ministerio de Ciencia e Innovación (PID2019-109215RB-C4-1 and PID2019-109215RB-C4-3) and the European Regional Development Fund. One of the authors (T. Tom) acknowledges the support of the Secretaria d'Universitats i Recerca de la Generalitat de Catalunya and European Social Fund (2019 FI_B 00456)., Peer Reviewed, Postprint (published version)

As optoelectronic devices continue to improve, control over film thickness has become crucial, especially in applications that require ultra-thin films. A variety of undesired effects may arise depending on the specific growth mechanism of each material, for instance a percolation threshold thickness is present in Volmer-Webber growth of materials such as silver. In this paper, we explore the introduction of aluminum in silver films as a mechanism to grow ultrathin metallic films of high transparency and low sheet resistance, suitable for many optoelectronic applications. Furthermore, we implemented such ultra-thin metallic films in Dielectric/Metal/Dielectric (DMD) structures based on Aluminum-doped Zinc Oxide (AZO) as the dielectric with an ultra-thin silver aluminum (Ag:Al) metallic interlayer. The multilayer structures were deposited by magnetron sputtering, which offers an industrial advantage and superior reliability over thermally evaporated DMDs. Finally, we tested the optimized DMD structures as a front contact for n-type silicon solar cells by introducing a hole-selective vanadium pentoxide (V2O5) dielectric layer., This research has been supported by the Spanish Ministerio de Economía, Industria y Competitividad and the European Regional Development Fund through the projects ENE2016-78933-C4-1-R, ENE2016-78933-C4-2-R, PID2019-109215RB-C41, PID2019-1092215RB-C43 and ENE2017-87671-C3-2-R. We acknowledge support of Secretaria d’Universitats i Recerca de la Generalitat de Catalunya and European Social Fund (2019 FI_B 00456)., Peer Reviewed, Postprint (published version)

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., Dielectric/metal/dielectric structures based on vanadium pentoxide with a thin silver interlayer have been optimized to replace traditional transparent electrodes. As would be expected, there is a tradeoff in the metal thickness to achieve high transparency and low sheet resistance simultaneously. It has been demonstrated that an ultra-thin gold seed prevents the tendency of silver to form clusters. This wetting effect reduces the metal thickness needed to form a continuous film, which leads to a higher averaged transmittance and very low sheet resistance. On the other hand, vanadium pentoxide on silicon forms a high-quality hole-selective contact. Thus, these structures can be used as an all-in-one transparent electrode and selective contact for a new kind of heterojunction solar cells. This concept has been proved in a 13.3% efficient solar cell fabricated on n-type silicon wafers. Besides being dopant-free, the complete fabrication route did not require any sputtered transparent electrode., Peer Reviewed, Postprint (author's final draft)

From: Phonologies of four Papua New Guinea languages, Loving, Richard, ed.: 45-96, 1974

Play opened September 24, 1976 at Kelly's Seed & Feed Theatre, Atlanta, Georgia. Full-text of the script: Title-page, [2] leaves, 29 numbered leaves. The script was loaned by Tom Cullen to Georgia State University for the creation of this digital object.

"Terminus," script and essay by Tom Cullen. Full text, essay, and photograph. First performed at Kelly's Seed & Feed Theater, Atlanta, Georgia, 1974. Play copyright 1977; essay copyright 2012.

Play opened September 24, 1976 at Kelly's Seed & Feed Theatre, Atlanta, Georgia. Full-text of the script: Title-page, [2] leaves, 29 numbered leaves. The script was loaned by Tom Cullen to Georgia State University for the creation of this digital object.

"Terminus," script and essay by Tom Cullen. Full text, essay, and photograph. First performed at Kelly's Seed & Feed Theater, Atlanta, Georgia, 1974. Play copyright 1977; essay copyright 2012.