In situ space-resolved X-ray diffraction and time-resolved EDXD on efficient polymer-based photovoltaic devices: Microst
- PDF / 1,111,050 Bytes
- 13 Pages / 584.957 x 782.986 pts Page_size
- 68 Downloads / 140 Views
Dipartimento di Fisica, Università di Roma “Tor Vergata” Via della Ricerca Scientifica 1, Italy
Amanda Generosi, Marco Guaragno, and Valerio Rossi Albertini Istituto di Struttura della Materia ISM-CNR, Via del Fosso del Cavaliere 100, Roma 00133, Italy
Claudio Ferrero ESRF—The European Synchrotron 71, av. des Martyrs, Grenoble Cedex 38043, France
Gianpaolo Susanna and Francesca Brunetti CHOSE-Center for Hybrid and Organic Solar Energy, Department of Electronics Engineering, Università di Roma, Tor Vergata, Via del Politecnico 1, Roma 00133, Italy
Ivan Davoli
Dipartimento di Fisica, Università di Roma “Tor Vergata” Via della Ricerca Scientifica 1, Italy
Barbara Pacia) Istituto di Struttura della Materia ISM-CNR, Via del Fosso del Cavaliere 100, Roma 00133, Italy (Received 20 June 2016; accepted 7 December 2016)
Microstructural and morphological features of the layers forming integrated PTB7/PC71BM organic solar cells with Ca/Al cathode are studied. The effects of vacuum treatment on properties and durability were addressed using complementary approaches: time-resolved experiments revealing the structural evolution of the active layers under illumination were conducted combining the in situ energy dispersive X-ray diffraction (EDXD) technique with atomic force microscopy (AFM); space-resolved characterization of the integrated devices was possible via high resolution X-ray diffraction, using a nano-focused synchrotron radiation X-ray beam to discriminate the device components. Active layers surface morphology is stable under illumination and PC71BM structural properties remain unaltered. PTB7 undergoes crystallinity depletion, mainly at the active layer/cathode interface. This effect is actually inhibited in the device submitted to vacuum treatment, proving that this procedure induces stabilization at the cathode’s buried interface, as verified by fourier transform infrared (FTIR) spectroscopy. Importantly, the protective role of the vacuum treatment results in a significant photovoltaic durability enhancement.
I. INTRODUCTION
An increasing investigation effort has been directed toward the study of polymer/fullerene-based organic solar cell (OSC) devices: flexibility, lightweight, transparency,1 and low-cost large-scale production representing their most appealing prospective benefits for a sustainable development.2–4 A fertile scientific research area has risen over the last years around polymer/fullerene cells5–8 and efficiencies have been recently improved up to more than 10%.9 This is an excellent result, however a large effort is still needed to enhance the devices’ lifetime. OSCs undergo plenty of degradation processes, both chemical,10–13 photochemical,14–16 and physical.17
Contributing Editor: Moritz Riede a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2016.500
Several solutions have been proposed to face this challenge: encapsulation with epoxy resins18 and multilayers19 among others. Furthermore, since the best operating nanostructure of the active layer may
Data Loading...
