Polymer solar cells mechanism

Fig. 4 Photoinduced charge transfer from a donor (here PPV) to an acceptor (here Ceo) serves as a highly efficient charge separation mechanism in most polymer solar cells [26]...

Dyakonov V (2004) Mechanisms controlling the efficiency of polymer solar cells. Appl Phys A 79 21... 

In this section we review theoretical and experimental results important for understanding the photophysics of polymer solar cells. We examine the states that are involved in the processes of photoinduced charge generation, and present a theoretical framework that describes the separation and recombination of charge-transfer states. Finally, we review the mechanisms for charge formation that operate in a fdm of a single conjugated polymer and the additional mechanisms, relevant to solar cell devices, that occur in binary donor acceptor blends. 

After splitting of the exciton at the heterojunction and further separation of the charge-transfer state, the charges (or polarons) need to be transported within the semiconductor materials network to the respective electrodes. Despite the recognition that it is mainly the separation of the charge-transfer states that limits current polymer polymer solar-cell devices, charge transport also has to be considered, because it is another potential loss mechanism. We will briefly cover this topic the interested reader is referred to a recent review by Blom et al. [7]. 

In order to understand the remarkable improvement of device efficiency introduced by BHJ structures, the working mechanism of polymer solar cells has to be clarified. The working mechanism of organic thin-film solar cells can be broken down as follows ... 

By these means, polymers are utilized to create new composite materials, which combine the good mechanical, electronic and optical properties of the two systems and find applications in solar cells, light emitting devices, sensors etc. The prepara-... 

Neugebauer H., Brabec C., Hummelen J. C. and Sariciftci N. S. (2000), Stabihty and photodegradation mechanisms of conjngated polymer/fullerene plastic solar cells . Solar Energy Mat. Solar Cells 61, 35 2. 

Although the first reports of this approach involved studies with metal alloys [3] and minerals [4], within a few years the technique has been extended to a wide variety of research areas. As these findings have been summarized in several reviews [5-8] and also in a monograph [9], attention will be focused here on more recent developments, notably on the mechanical immobilization of particles on electrodes. Today, a huge amount of information is available for electrochemical systems comprising particles enclosed in polymer films or other matrices (see Refs [10-16]). Originally, the main aim of such particle enclosure was to achieve specific electrode properties (e.g., functionalized carbon/polymer materials as electrocatalysts [17, 18] solid-state, dye-sensitized solar cells [19]), rather than to study the electrochemistry of the particles. This situation arose mainly because the preparation of these composites was too cumbersome for assessing the particles properties. The techniques also suffered from interference caused by the other phases that constituted the electrode. 

The PL efficiency for PPV alone was measured to be 20%. This proves the PPV luminescence quenching. From point of review of photoactive materials, such a composite as PPV+nc-Ti02 can be used for excitonic solar cells. The mechanism of the PPV luminescence quenching effect has been elucidated by energy diagram of polymer/ oxide junctions (Figure 6). 

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