Bulk-heterojunction photovoltaic

Peumans, P. Uchida, S. Forrest, S. R. 2003. Efficient bulk heterojunction photovoltaic cells using small-molecular-weight organic thin films. Nature 425 158-162. 

Besides ruthenium complexes, rhenium complexes were also used as the photosensitizers in photovoltaic cells. Bulk heterojunction photovoltaic cells fabricated from sublimable rhenium complexes exhibited a power conversion efficiency of 1.7%.75,76 The same rhenium complex moiety was incorporated into conjugated polymer chains such as polymer 16a c (Scheme 9). Fabrication of devices based on conjugated rhenium containing polymers 17a c and SPAN by the LbL deposition method was reported.77 The efficiencies of the devices are on the order of 10 4%. 

In a bulk-heterojunction photovoltaic cell with methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM) as an electron acceptor, alternating copolymer 19 (Fig. 9), derived from 2,7-fluorene and 2,5-dithienylsilole, can show impressive performance as the electron donor.31 In a device configuration of ITO/PEDOT/active layer/Ba/Al, the dark current density—bias curve shows a small leakage current, suggesting a continuous, pinhole-free active layer in the device. Under illumination of an AM 1.5 solar simulator at 100 mW/cm2, a high short-circuit current of 5.4 mA/cm2, an open-circuit voltage of 0.7 V, and a fill factor of 31.5% are achieved. The calculated energy conversion efficiency is 2.01%. 

For proper operation of a bulk heterojunction photovoltaic cell, a special alignment of the HOMO and LUMO levels of the bulk heterojunction components must be accomplished, compatible with the electrodes work functions, as depicted in Scheme 5.8. If an exciton is formed in the polymer phase, then the electron is transferred to the NC phase and reaches the aluminum electrode via its percolating pathway. The remaining hole is transported to the ITO electrode through the polymer phase. In the alternative case, that is, the formation of an exciton in the NCs phase, the hole is transferred to the polymer phase and then transported to the ITO electrode, whereas the electron reaches the aluminum electrode through the NCs phase. 

The use of Pt-acetylides containing phosphine ligands was extended further by the Schanze group in 2006 [84, 85], In one contribution, they incorporated platinum-acetylide polymers into photovoltaic devices which demonstrate good device efficiency. Transient absorption studies provide definitive evidence for photoinduced electron transfer from the Pt-acetylide to PCBM by the temporal evolution of the TA spectrum, observing the formation of the PCBM radical anion at 1,050 nm. The same system was eventually demonstrated to operate as a bulk heterojunction photovoltaic device [84],... 

Shaheen SE, Brabec CJ, Sariciftci NS, Jabbour GE (2001) Effects of inserting highly polar salts between the cathode and active layer of bulk heterojunction photovoltaic devices. Presented at the Materials Research Society meeting, San Francisco. MRS Proc 665 C5511... 

Wienk MM, Kroon JM, Verhees WJH, Knol J, Hummelen JC, van Hall PA, Janssen RAJ (2003) Efficient methano[70]fullerene/MDMO-PPV bulk heterojunction photovoltaic cells. Angew Chem Int Ed 42 3371... 

Yang, R, Shtein, M., and Forrest, S.R., Controlled growth of a molecular bulk heterojunction photovoltaic cell, Nat. Mater. 4, 37 1, 2005. 

Gebeyehu, D., Maennig, B., Drechsel, J., Leo, K., and Pfeiffer, M. 2003. Bulk-heterojunction photovoltaic devices based on donor-acceptor organic small molecule blends. Solar Energy Materials and Solar Cells 79 (l) 81-92. 

J. Li, M. Kastler, W. Pisula, J.W.F. Robertson, D. Wasserfallen, A. Clive, G. Grimsdale, J. Wu, K. Mtillen, Organic bulk-heterojunction photovoltaics based on alkyl substituted discotics. Adv. Funct. Mater. 17, 2528-2533 (2007)... 

K. M. Noone, E. Strein, N. C. Anderson, P.-T. Wu, S. A. Jenekhe, D. S. Ginger, Broadband Absorbing Bulk Heterojunction Photovoltaics Using Low-Bandgap Solution-Processed Quantum Dots. Nano Letters 2010, 10, 2635-2639. 

Y.-Y. Lin, et al.. Improved performance of polymer/TiOjsub 2] nanorod bulk heterojunction photovoltaic devices by interface modification. Applied Physics Letters, 2008. 92(5) p. 053312-3. 

Hybrid films of ZnO nanoparticles and poly[2-methoxy - 5 - (3, 7 -dimethyloctyloxyl) -1,4-phenylene vinylene] (MDMO-PPV) have been characterized as a model hybrid bulk heterojunction photovoltaic cell [145]. 

Ishikawa, T., M. Nakamura, K. Fujita, and T. Tsutsui. 2004. Preparation of organic bulk heterojunction photovoltaic cells hy evaporative spray deposition from ultradilute solution. Appl Phys Lett 84 2424. 

Chen, I.W. and Cao, Y. (2009) Development of novel conjugated donor polymers for high-effidency bulk-heterojunction photovoltaic devices. Acc. Chem. Res., 42 (11), 1709-1718. 

Swaraj, S., Wang, C., Yan, FI., Watts, B., Luning, J., McNeill, C.R., and Ade, H. (2010) Nanomorphology of bulk heterojunction photovoltaic thin films probed with resonant soft X-ray scattering. Nano Lett., 10, 2863-2869. 

Gupta, D., Kabra, D., Kolishetti, N., Ramakrishnan, S., and Narayan, K.S. (2007) An effident bulk-heterojunction photovoltaic cell based on energy transfer in graded-bandgap polymers. Adv. Funct. Mater., 17, 226-232. 

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