Photoresponse of nanostructures for advanced photovoltaic applications  

Project leaders

Isodiana Crupi, Antonín Fejfar

Agreement

REPUBBLICA CECA - CAS (ex AVCR) - Czech Academy of Sciences

Call

CNR/AVCR 2013-2015

Department

Materials and Devices

Thematic area

Physical sciences and technologies of matter

Status of the project

New

Research proposal

Global warming, climate change and fossil fuel shortage problems have strengthened the need to promote renewable energies like photovoltaics (electricity from sunlight, the most abundant energy source on the planet). Photovoltaics industry is growing rapidly and it is attracting widespread interest for ongoing innovations and improvements in the field of materials and devices. One of the key goals in the photovoltaics industry is to achieve high efficiency devices while simultaneously reducing manufacturing costs. Since of their intriguing optical and electrical properties favoring photon broadband absorption and photocarrier collection, nanostructures may be a powerful tool towards next-generation, high efficiency, cost-effective photovoltaics cells.
Interaction of light with nanostructures is the underlying principle of light trapping in the nanostructured solar cells and is being used in many other photonic structures. Research in this field is therefore strongly motivated and has been actively pursued in both the Italian and Czech teams who have a broad background in both semiconducting and conducting nanostructures. These include Si nanocrystals, Si nanowires and nanostructured Si thin films, as well as metallic nanoclusters and nanostructured transparent conductive oxides (TCO). Combination of nanostructured conductors serving as contacts to the active semiconductor absorber layers offers ways for photon management in the novel types of solar cells.
Both the Italian and Czech groups have excellent experimental equipment and wide base of know how. In particular, the team in Prague has deposition systems for preparation of Si thin films and nanostructures, either using Plasma-Enhanced Chemical Vapor Deposition (PECVD) techniques, Vapor Liquid Solid (VLS) method or using the anodic etching of Si wafers. The team at CNR has a wide experience in synthesis by RF magnetron sputtering and post annealing process of Ag nanoclusters and TCO films, including multilayers. Both teams are equipped for performing optical and structural characterization of nanostructures and electrical measurements on devices.
Both teams seek to establish a wider cooperation, possibly leading to submission of joint research proposals.
A promising method for efficient light trapping in thin film solar cells can be the use of metallic nanoparticles that can effectively scatter sunlight thanks to Localized Surface Plasmon Resonance (LSPR). Initially, CNR shall focus on preparation of self assembled Ag nanoclusters. AVCR shall focus on preparation of Si nanostructures by plasma activated VLS method using the metallic nanoparticles as seed layers. The main interest here is to achieve selective growth of nanowires at predefined positions. Another approach would be decoration of the prepared multilayers by semiconducting nanoparticles. The exchange of samples will be followed by specialized measurements for which visits of researchers from both sides are planned. The samples will be characterized by local measurements of electronic properties using conductive atomic force microscopy and/or Kelvin force microscopy. A detailed optical characterization of such nanostructures will be carried out through measurements of absolute values of total as well as scattered and diffused parts of transmittance (T) and reflectance (R) by using an UV/VIS/NIR spectrophotometer with integrating sphere.
The present frontier of this research is measurements of local photoresponse as a function of the nanostructure.  For this purpose, the CNR group will be using: Varian Cary 500 double beam scanning UV/Vis/NIR spectrophotometer; Gemini Field Emission SEM (FE-SEM) Carl Zeiss SUPRA™ 25; Veeco Innova Atomic Force Microscope; Rutherford Backscattering Spectrometry (RBS); JEOL 2010-F Field Emission Transmission electron microscopy (TEM). The team at AVCR will be using the existing facilities which include: Bruker Icon SPM with C-AFM, KPFM etc.; Veeco Dimension 3100 AFM equipped TUNA; Renishaw Raman microspectroscopy combined with NT MDT nTegra Spectra AFM and Linkam Examina temperature stage; Tescan Mira field emission gun SEM.
The project will be divided into 4 workpackages:
1)      Synthesis of metal nanoclusters and TCO/metal/TCO multilayers – Responsible: CNR
2)      Synthesis of nanostructured Si thin films and TCO nanostructures – Responsible: AVCR
3)      Structural characterization (RBS, SEM, AFM, TEM) – Responsible: CNR
4)      Optical microspectroscopy (Raman and UV/VIS/NIR spectroscopy) – Responsible: AVCR
Planned scope exchanges is the same on both sides, and 14 days residence of the Czech Republic in Italy and vice versa.
 
 
 
 
 

Research goals

The use of nanostructures in photovoltaics offers the potential for high efficiency solar cells with low fabrication costs. Low-dimensional quantum structures have shown to have unique optical and electronic properties.
The main objectives of this proposal are to suitably design and synthesize, both semiconducting and conducting nanoparticles, and to deeply investigate the photoresponse of such structures. At the end of the project we expect to achieve promising nanostructures for advanced solar cell applications.
Last but not least the project will also establish research networks and collaborations between Italian and Czech Republic scientists, who gain a considerable knowledge in the subject, and high-level joint publications.
 

Last update: 25/04/2024