By Prof. Dr. Ahmed Ennaoui, Research Director at Qatar Environment and Energy Research Institute, Qatar Foundation & Full Professor at College of Science and Engineering, Hamad bin Khalifa University (HBKU), Education City, Doha/Qatar.
Inkjet printing is a promising technology enabling the development of efficient thin film PV technology based on low cost materials and processes. Similar to a common inkjet printing process, printable solar panel thin film manufacturing of solar PV allows negligible materials waste and significant reduction of raw materials cost. This technology can produce any type of printable material on metal, ceramic, glass, plastic, foil, and in any shape. Furthermore, inkjet printing can be easily adapted to Roll-to-Roll (R2R) processing, which is suitable for large scale production. Recently we developed new approach consisting of Ink formulation and drop-on-demand (D-O-D) inkjet printing for the deposition of copper zinc tin sulfoselenide (Cu2ZnSnSexS4-x, or simply CZTSS)  and copper Indium-Gallium sulfoselenide (Cu(In,Ga)(SeS)2, or simply CIGSS)  . In this talk, the use of inkjet printing to deposit thin film structures will be described, and the advantages of D-O-D inkjet explained for the fabrication of CZTSS and CIGSS solar cells using D-O-D method. Highly efficient precursor utilization, vacuum-free, and scalable route for the deposition of CZTSS and CIGSS thin films absorbers and buffer  will be discussed. We were able to use less than 20 microliter ink to build up a micrometer thin film absorber on an inch by inch substrate, this is a dramatic reduction in wasted material. A solar cell with a total area efficiency of 11.3% under standard AM 1.5 illumination has been achieved based on the printed CIGSSe absorbers. Manufacturing functional ink produced from salt precursors with tuned viscosity and surface tension of the ink at a molecular level to sit within the printability range is targeted. The final goal is to produce monolithically integrated inkjet printing technology for emerging PV technolocy, with high efficiency, negligible materials waste and significant reduction of raw materials cost, without relying on expensive vacuum technology.
 Xianzhong Lin, Jaison Kavalakkatt, Martha Ch. Lux-Steiner, and Ahmed Ennaoui,
Advanced Sciences (2015), Vol. 2, Issue 6, DOI: 10.1002/advs.201500028
 X. Lin, R. Klenk, L. Wang, T. Köhler, J. Albert, S Fiechter, A. Ennaoui, Energy & Environmental Science (2016) 9 (6), 2037-2043. DOI: 10.1039/C6EE00587J
 Lan Wang, Xianzhong Lin, Ahmed Ennaoui, Christian Wolf, Martha Ch. Lux-Steiner, and Reiner Klenk. EPJ Photovoltaics, 7, 70303 (2016)
Ahmed Ennaoui serves as research director at Qatar Environment and Energy Research Institute (QEERI), and faculty member in the College of Science and Engineering (CSE), at the rank of Joint full professor at Hamad Bin Khalifa University (HBKU). He is teaching, conducting research, managing research team, and recruiting top scientists. The objective is to deliver more efficient, scalable, and cheaper clean energy technologies. Ennaoui studied and graduated with a doctorate at the Universities of Bourgogne in the field of solid state electronic. In his dissertation he explored TiO2 single crystal photoanode for water splitting. After several years of teaching in Moroccan Universities, he moved to Germany and worked with Prof. Helmut Tributsch at “Hahn-Meitner-Institut-Berlin (HMI), Abteilung Solare Energetik und Materialforschung“,he completed his Habilitation on iron disulfide FeS2 for solar energy conversion, then he worked as Postdoc, and as senior scientist at HMI, exploring transition metal chalcogenides and 2D Van der Waals (VdW) layered materials, photoelectrochemical etching to reduce the density of surface states in hydrogen terminated Silicon. He was then appointed as head of research group in the institute of Heterogeneous Material systems at Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) for almost 25 years conducting research on thin film solar cells, particularly Cadmium free CIGS, and low cost CZTS solar cells. In his role at HZB, Ennaoui was responsible for the set-up and operation of state-of-the-art laboratory with capabilities for low cost processing of novel materials, non vacuum and (photo)-electrochemical methods. Ennaoui also served as full professor of physics at University Mohamed V (Morocco), and as visiting Professor at Osaka University, he taught several courses in Quantum Physics/Statistical Physics, Material sciences, Photovoltaic and Photo-electrochemistry. Ennaoui was active in using scientific research as a bridge between Morocco and different countries, he was helping many Moroccan graduate students to work abroad. He managed for several PhD students to obtain the Sandwich scholarship for completing PhD and Habilitation degrees in Germany, UK, Belgium and Japan. During his career at HZB, he managed in his group several European research projects, (JOULE II, CISLINE, NEBULES, ATHLET, CHEETAH), as well as several projects financed by the German Federal Ministry of Education and Research, BMBF (NEUMAS, NANOPV). He also conducted several feasibility studies with industry partners (Atotech, Siemens Solar, Avancis, Bosh-Solar). He invented and patented new Cadmium free buffer layers for thin film Cu-chalcopyrite solar cell and achieving high efficiency solar cells (above 16% efficiency for lab scale). He worked solving industry-oriented topics to reduce the Fab-to-Lab gap and he obtained 13% for large-scale modules (120cmx60cm). His research interest includes advanced materials, non-vacuum techniques, nanosynthesis, photoelectrochemistry, and solid-state devices. Actually, he is exploring ink formulation and processing Cu(In,Ga)(S,Se)2 and Cu2ZnSn(S,Se)4 for Inkjet printing solar cell. He achieved in collaboration with his partners in Germany, solar cell with efficiency above 11% and 6% for CIGS and CZTS respectively. He has published more than 200 research papers and several patents (with h-index 36). He is serving as president of the scientific council of IRESEN (Institut de Recherche en Energie Solaire et Energies Nouvelles). He is permanently serving in the Editorial Board of Solar Energy Materials and Solar Cells. He is member of EU-PVTP and served as referee for scientific evaluation and expertise of research proposal for Technology Foundation STW (Dutch funding agency for academic research in the field of applied sciences) and scientific evaluation and expertise of the program “sinergia” lunched by “Schweizerische National fonds(SNF)”.