State-of-the-art MDMO-PPV:PCBM bulk heterojunction organic solar cells: materials, nanomorphology, and electro-optical properties

Abstract

Current state-of-the-art bulk hetero-junction organic photovoltaic devices will be discussed based on poly(2-methoxy-5-(3',7'-dimethyl-octyloxy))-p-phenylene vinylene, (MDMO-PPV), as an electron donor and (6,6)-phenyl-C61-butyric-acid (PCBM) (a soluble C60 derivative) as electron acceptor. A brief review will be provided summarizing recent results on efficiency enhancement and on morphological investigations. A significant increase in power conversion efficiency has been demonstrated for devices based on so-called 'sulphinyl' synthesised MDMO-PPV (T1AMI.5 _ 2.9%) in comparison with devices based on 'Gilch' synthesised MDMO-PPV (1I5 2.5%). In order to understand the higher efficiency values obtained using a different solvent or a different MDMO-PPV-material, electrical and morphological investigations are being performed. Concerning the latter, it has been shown with various analytical techniques that the morphology of the blended photoactive films and also the power conversion efficiency of the corresponding photovoltaic devices are both simultaneously influenced by preparation conditions such as choice ofthe solvent and drying conditions.

Polyphenylene-Based Materials for Organic Photovoltaics

“…The photophysics of a bilayer of poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV, compound 7 (Chart )) with C 60 was first reported in 1992. , The experiments clearly evidenced an ultrafast, reversible, metastable photoinduced electron transfer from MEH-PPV to C 60 in solid films. This result accelerated the development of polymer solar cells for many years, and poly[2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylene vinylene] (MDMO-PPV, compound 8 ) is still being used in organic solar cells today. − Combined with 1-[3-(methoxycarbonyl)propyl]-1-phenyl-(6,6)-C 61 (PCBM), efficiencies of MDMO-PPV-based solar cells of up to 2.9% could be obtained. , …”

“…Regarding the outstanding photovoltaic performance of polyphenylenevinylene and its derivatives shown in polymer solar cells, , the oligo( p -phenylenevinylene)s have also been used as bridges between donor and acceptor groups. Ko and co-workers have reported oligophenylenevinylenes 73 − 75 (Chart ) which were functionalized with bis(9,9-dimethyl-9H-fluoren-2-yl)amine groups (D) and cyanoacrylic acid units (A) .…”

“…[107][108][109][110][111][112][113] Combined with 1-[3-(methoxycarbonyl)propyl]-1-phenyl-(6,6)-C 61 (PCBM), efficiencies of MDMO-PPVbased solar cells of up to 2.9% could be obtained. 114,115 Although PPV is well-known as a donor material in solar cell devices, a cyano derivative of PPV (compound 9; Chart 4) was used as the first polymer electron acceptor. 116 By using a lamination device processing technique, 117 Friend et al reported a two-layer polymer cell based on compound 9 and polythiophene 10.…”

Morphology and energy transfer study between conjugated polymers thin films: experimental and theoretical approaches

“…The homopolymer MDMO-PPV is one of the pioneering in organic electronic devices, both in the light emitting diode and photovoltaic cell application [21]. In this context, the material's price has decreased and nowadays the MDMO-PPV has one of the lowest prices compared to others conjugated polymers [22]. However, the narrow absorption range limited the PPV derivatives PCEs [23].…”

“…The so-called OSCs are a new class of low-cost and easy to manufacture renewable energy. In addition to these properties, the organic semiconductor has a high absorption coefficient, enabling the production of lightweight and flexible devices [22,23]. Despite the great advantages of OSCs, the photocurrent process in organic semiconductors remains unclear.…”