Polymer/Nanocrystal Hybrid Solar Cells: Influence of Molecular Precursor Design on Film Nanomorphology, Charge Generation and Device Performance
The morphological and optoelectronic properties of polymer/nanocrystal hybrid (pnh) solar absorber layers can be significantly influenced by small modifications of the chemical structures of the precursor molecules. Pnh solar cells are an interesting concept due to the incorporation of the attractive qualities of both organic and inorganic materials.
A. J. MacLachlan et al. ,Adv. Funct. Mater. 25, 409 (2015).
Figure 1. Chemical structures of the used cadmium xanthate and the different alkyl moieties, TEM images of poly(3-hexylthiophene)/CdS hybrid layers prepared using a xanthate bearing a propyl (upper image) and a dimethylpentyl (bottom image) alkyl chain and the current/voltage characteristics of the corresponding hybrid solar cells (green: propyl, purple: dimethylpentyl). |
Moreover, the influences of the different nanomorphologies on the optoelectronic properties of the films are studied by microsecond and femtosecond transient absorption spectroscopy and a remarkable effect on device performance is revealed. While in finer mixed morphologies down to a certain domain size more efficient photoinduced charge generation was observed, the highest power conversion efficiencies were obtained in solar cells prepared using metal xanthates bearing propyl moieties, which have an absorber layer nanomorphology with medium sized domains. This originates from the fact that besides efficient charge generation also charge transport and recombination play a crucial role in the devices, which become more and more an issue when going to finer mixed morphologies.
Figure 2. a) GIWAXS patterns of a polymer/Cd-butyl xanthate sample measured between 22.9 and 35° 2 theta during a heating run from room temperature to 200°C showing the evolution of the most intense peak of CdS at around 27° 2 theta. The increasing temperature (T) is indicated with a black arrow; b) Normalised integrated intensity of the GIWAXS patterns of the different samples plotted against time and temperature; c) GISAXS images of the ethyl and butyl xanthate samples at different temperatures during the heating run. Retrieve articlePolymer/Nanocrystal Hybrid Solar Cells: Influence of Molecular Precursor Design on Film Nanomorphology, Charge Generation and Device Performance;A.J. MacLachlan, T. Rath, U.B. Cappel, S.A. Dowland, H. Amenitsch, A.-C. Knall, C. Buchmaier, G. Trimmel, J. Nelson and S.A. Haque Adv. Funct. Mater. 25, 409 (2015); 10.1002/adfm.201403108 |