Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 27: Photovoltaics: Innovative Material Systems

HL 27.3: Talk

Tuesday, March 27, 2012, 10:00–10:15, ER 270

Insights into the growing mechanism of electrocrystallised ZnO — •Miriam Schwarz, Karolis Parfeniukas, and Veit Wagner — School of Engineering and Science, Jacobs University Bremen, Campusring 1, D-28759 Bremen (Germany)

Hybrid approaches to solar cells, offer the combined advantage of high mobilities of inorganics with tailored design of organic / polymeric materials in one device. A well designed inorganic scaffold is desired in which the organic material can be embedded. This scaffold requires on one hand, a dense inorganic layer as blocking layer at the interface to the cathode, on the other hand, rods of a high aspect ratio and proper spacing on top to offer a large interface to the organic material. Such well designed hybrid solar cells are expected to outperform fully organic photovoltaics by minimizing tortuous pathways for charges to the appropriate electrodes, typical for organic devices. In this context, we report on the morphological control of crystalline ZnO deposited by electrochemistry at low temperatures (< 100 °C). We relate the time dependent deposition current of the main deposition parameters to certain stages of ZnO growth. Since nucleation occurs extremely fast, the first few seconds (< 15 s) are of special interest. Thus, the analysis of the growing mechanism reveals a rather weak voltage and a strong temperature and concentration dependence. Consequently, tuning the temperature and concentration allows to design the crystal density and shape of the ZnO nanostructures for appropriate hybrid solar cell application.