Growth kinetics of colloidal Ge nanocrystals for light harvesters. Issue 44 (18th April 2016)

• Record Type: Journal Article
• Authors: Cosentino, Salvatore; Torrisi, Giacomo; Raciti, Rosario; Zimbone, Massimo; Crupi, Isodiana; Mirabella, Salvo; Terrasi, Antonio
• Is Part Of: RSC advances. Volume 6:Issue 44(2016)
• Page Start: 38454
• Page End: 38462
• Publication Date: 2016-04-18
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c6ra03490j
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : Representation of growth kinetics mechanisms that strongly control synthesis and final dimension of colloidal nanocrystals. Abstract : Colloidal Ge nanocrystals (NCs) are gaining increased interest because of their potential application in low-cost optoelectronic and light harvesting devices. However, reliable control of colloidal NC synthesis is often an issue and a deeper understanding of the key-role parameters governing NC growth is highly required. Here we report an extended investigation on the growth of colloidal Ge NCs synthesized from a one-pot solution based approach. A systematic study of the effects of synthesis time, temperature and precursor concentration is elucidated in detail. X-ray diffraction (XRD) analysis reveals the presence of crystalline Ge NCs with a mean size (from 5 to 35 nm) decreasing with the increase of precursor concentration. Such a trend was further confirmed by scanning electron microscopy (SEM) and dynamic light scattering (DLS) analysis. Moreover, the temporal NC size evolution shows a typical saturating behaviour, where characteristic time shortens at higher precursor concentration. All these growth features were satisfactorily simulated by a numerical NC growth model, evidencing that the kinetics of NC growth is controlled by a reaction-limited regime with typical activation energy of 0.7 eV. Finally, light absorption in the visible region and the successful realization of a hybrid photodetector, employing colloidal Ge NCs embedded in PEDOT:PSS polymer, showed the capability of low-cost colloidal Ge to act as light harvester. These results put new understanding for a reliable control of colloidal NC growth and the development of low-cost devices.