The magic world of nanocrystals, from batteries to solar cells

Michael Gr?tzel 한국물리학회 2006 Current Applied Physics Vol.6 No.1l

tungsten trioxide niobium oxide and titanium dioxide, which are interconnected to allow for electronic conduction to take place. Thepores between the particles are lled with a semiconducting or a conducting medium, such as a p-type semiconductor, a polymer, a holetransmitter or an electrolyte, constituting a junction of extremely large contact area. In this way interpenetrating bicontinuous networkcomposites are formed which are phase-separated by a heterojunction. Electrons can percolate rapidly across the network of nanopar-of important applications. Of particular interest are high power lithium insertion batteries and dye-sensitized solar cells (DSC). The latterhave emerged as credible alternatives to conventional silicon based devices. The transparent nature of these lms and the high conversioneciency oers new opportunities for applications, e.g., as electric power producing windows. Mesoscopic oxide semiconductor lmsoer also great promise for a new generation of electroluminescent and electrochromic systems. Examples of these devices will be pre-sented and their mode of operation will be discussed

레이저를 이용한 MICRO-LED 가공

Rainer Pä,tzel 한국레이저가공학회 2018 Laser Solutions Vol.21 No.12

Fine-tuning the Electronic Structure of Organic Dyes for Dye-Sensitized Solar Cells

Gao, Peng,Tsao, Hoi Nok,Grä,tzel, Michael,Nazeeruddin, Mohammad K. American Chemical Society 2012 Organic letters Vol.14 No.17

<P>A series of metal-free organic dyes exploiting different combinations of (hetero)cyclic linkers (benzene, thiophene, and thiazole) and bridges (4<I>H</I>-cyclopenta[2,1-<I>b</I>:3,4-<I>b′</I>]dithiophene (CPDT) and benzodithiophene (BDT)) as the central π-spacers were synthesized and characterized. Among them, the sensitizer containing the thiophene and CPDT showed the most broad incident photon-to-current conversion efficiency spectra, resulting in a solar energy conversion efficiency (η) of 6.6%.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/orlef7/2012/orlef7.2012.14.issue-17/ol301730c/production/images/medium/ol-2012-01730c_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ol301730c'>ACS Electronic Supporting Info</A></P>

Growth of CH₃NH₃PbI₃ cuboids with controlled size for high-efficiency perovskite solar cells

Im, Jeong-Hyeok,Jang, In-Hyuk,Pellet, Norman,Grä,tzel, Michael,Park, Nam-Gyu Nature Publishing Group, a division of Macmillan P 2014 Nature nanotechnology Vol.9 No.11

Perovskite solar cells with submicrometre-thick CH<SUB>3</SUB>NH<SUB>3</SUB>PbI<SUB>3</SUB> or CH<SUB>3</SUB>NH<SUB>3</SUB>PbI<SUB>3–</SUB><SUB>x</SUB>Cl<SUB>x</SUB> active layers show a power conversion efficiency as high as 15%. However, compared to the best-performing device, the average efficiency was as low as 12%, with a large standard deviation (s.d.). Here, we report perovskite solar cells with an average efficiency exceeding 16% and best efficiency of 17%. This was enabled by the growth of CH<SUB>3</SUB>NH<SUB>3</SUB>PbI<SUB>3</SUB> cuboids with a controlled size via a two-step spin-coating procedure. Spin-coating of a solution of CH<SUB>3</SUB>NH<SUB>3</SUB>I with different concentrations follows the spin-coating of PbI<SUB>2</SUB>, and the cuboid size of CH<SUB>3</SUB>NH<SUB>3</SUB>PbI<SUB>3</SUB> is found to strongly depend on the concentration of CH<SUB>3</SUB>NH<SUB>3</SUB>I. Light-harvesting efficiency and charge-carrier extraction are significantly affected by the cuboid size. Under simulated one-sun illumination, average efficiencies of 16.4% (s.d. ± 0.35), 16.3% (s.d. ± 0.44) and 13.5% (s.d. ± 0.34) are obtained from solutions of CH<SUB>3</SUB>NH<SUB>3</SUB>I with concentrations of 0.038 M, 0.050 M and 0.063 M, respectively. By controlling the size of the cuboids of CH<SUB>3</SUB>NH<SUB>3</SUB>PbI<SUB>3</SUB> during their growth, we achieved the best efficiency of 17.01% with a photocurrent density of 21.64 mA cm<SUP>–2</SUP>, open-circuit photovoltage of 1.056 V and fill factor of 0.741.

Rutile TiO2-based perovskite solar cells

Lee, Jin-Wook,Lee, Taek-Yong,Yoo, Pil J.,Grä,tzel, Michael,Mhaisalkar, Subodh,Park, Nam-Gyu The Royal Society of Chemistry 2014 Journal of Materials Chemistry A Vol.2 No.24

Modulating dye <i>E</i>_(S+/S*) with efficient heterocyclic nitrogen containing acceptors for DSCs

Delcamp, Jared H.,Yella, Aswani,Nazeeruddin, Mohammad K.,Grä,tzel, Michael The Royal Society of Chemistry 2012 Chemical communications Vol.48 No.17

<P>Acceptor motifs based on nitrogen containing heterocycles have been synthesized for use in dye-sensitized solar cells (DSCs). Through the selective addition of nitrogen atoms and increased conjugation of the nitrogen containing heterocycles the excited-state oxidation potential, <I>E</I><SUB>(S+/S*)</SUB>, may be conveniently tuned with minimal effect on the ground-state oxidation potential, <I>E</I><SUB>(S+/S)</SUB>, of the dye.</P> <P>Graphic Abstract</P><P>A series of nitrogen containing heterocyclic acceptors are shown to tune the excited-state oxidation potential of D-π-A dyes for DSCs. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2cc17142b'> </P>

Thermal Behavior of Methylammonium Lead-Trihalide Perovskite Photovoltaic Light Harvesters

Dualeh, Amalie,Gao, Peng,Seok, Sang Il,Nazeeruddin, Mohammad Khaja,Grä,tzel, Michael American Chemical Society 2014 Chemistry of materials Vol.26 No.21

<P>Recently organic–inorganic hybrid perovskites have attracted attention as light harvesting materials in mesoscopic cells. While a considerable number of deposition and formation methods have been reported for the perovskite crystalline material, most involve an annealing step. As such, the thermal behavior of this material and its individual components is of crucial interest. Here, we examine the thermal properties of the CH<SUB>3</SUB>NH<SUB>3</SUB>PbX<SUB>3</SUB> (X = I or Cl) perovskite using thermogravimetric analysis. The role of the precursors is exposed, and the effect of the formation of excess organic species is investigated. The sublimation behavior of the organic component is intensively scrutinized. Furthermore, differential scanning calorimetry is employed to probe the crystal phase structure, revealing subtle differences depending on the deposition method.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2014/cmatex.2014.26.issue-21/cm502468k/production/images/medium/cm-2014-02468k_0004.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm502468k'>ACS Electronic Supporting Info</A></P>

Modeling Ruthenium-Dye-Sensitized TiO₂ Surfaces Exposing the (001) or (101) Faces: A First-Principles Investigation

De Angelis, Filippo,Vitillaro, Giuseppe,Kavan, Ladislav,Nazeeruddin, Mohammad. K.,Grä,tzel, Michael American Chemical Society 2012 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.116 No.34

<P>We present a first-principles computational investigation on the adsorption mode and electronic structure of the highly efficient heteroleptic ruthenium dye C101, [NaRu(4,4′-bis(5-hexylthiophene-2-yl)-2,2′-bipyridine)(4-carboxylic acid-4′-carboxylate-2,2′-bipyridine)(NCS)<SUB>2</SUB>], on anatase TiO<SUB>2</SUB> models exposing the (001) and (101) surfaces. The electronic structure of the TiO<SUB>2</SUB> models shows a conduction band energy upshift for the (001)-surface ranging between ∼50 and ∼110 meV compared with the (101) surface, in agreement with previous interfacial impedance and recent spectro-electrochemical data. TDDFT excited-state calculations provided the same optical band gap, within 0.01 eV, for the (001)- and (101) models. Two dominant adsorption modes for C101 dye adsorption on the (001) and (101) surfaces were found, which differ by the binding of the dye carboxylic groups to the TiO<SUB>2</SUB> surfaces (bridged bidentate vs monodentate), leading to sizably different tilting of the anchoring bipyridine plane with respect to the TiO<SUB>2</SUB> surface. The different adsorption mode leads to a smaller dye coverage on the (001) surface, as experimentally found, due to partial contact of the thiophene and alkyl bipyridine substituents with the TiO<SUB>2</SUB> surface. For the energetically favored adsorption modes, we calculate a larger average spatial separation, by 1.3 Å, between the dye-based HOMO and the semiconductor surface in (001) and (101) TiO<SUB>2</SUB> models. In terms of simple nonadiabatic electron-transfer considerations, our model predicts a retardation of the charge recombination kinetics, in agreement with the experimental observations.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2012/jpccck.2012.116.issue-34/jp306186y/production/images/medium/jp-2012-06186y_0008.gif'></P>

Perovskite Solar Cells with 12.8% Efficiency by Using Conjugated Quinolizino Acridine Based Hole Transporting Material

Qin, Peng,Paek, Sanghyun,Dar, M. Ibrahim,Pellet, Norman,Ko, Jaejung,Grä,tzel, Michael,Nazeeruddin, Mohammad Khaja American Chemical Society 2014 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.136 No.24

<P>A low band gap quinolizino acridine based molecule was designed and synthesized as new hole transporting material for organic–inorganic hybrid lead halide perovskite solar cells. The functionalized quinolizino acridine compound showed an effective hole mobility in the same range of the state-of-the-art spiro-MeOTAD and an appropriate oxidation potential of 5.23 eV vs the vacuum level. The device based on this new hole transporting material achieved high power conversion efficiency of 12.8% under the illumination of 98.8 mW cm<SUP>–2</SUP>, which was better than the well-known spiro-MeOTAD under the same conditions. Moreover, this molecule could work alone without any additives, thus making it to be a promising candidate for solid-state photovoltaic application.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2014/jacsat.2014.136.issue-24/ja503272q/production/images/medium/ja-2014-03272q_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja503272q'>ACS Electronic Supporting Info</A></P>

Functionalized alkyne bridged dendron based chromophores for dye-sensitized solar cell applications

Baek, Nam Seob,Yum, Jun-Ho,Zhang, Xianxi,Kim, Hwan Kyu,Nazeeruddin, Mohammad K.,Grä,tzel, Michael Royal Society of Chemistry 2009 Energy & environmental science Vol.2 No.10

<P>We report the results of an investigation on the preparation, spectral and photoelectrochemical properties of alkyne bridged dendron chromophores with carboxylic acid anchoring group, which adhere effectively to nanocrystalline (anatase) TiO<SUB>2</SUB> surfaces yielding incident photon-to-current conversion efficiency values of up to 76% in their photocurrent action spectra, suggesting that the alkyne π-bridge functional moiety is an effective bridging group between chromophore and conduction band of the semiconductor.</P> <P>Graphic Abstract</P><P>Alkyne bridged dendron chromophores with carboxylic acid anchoring group exhibit superior incident photon-to-current conversion efficiency and enhanced red response compared to the alkene π-bridged chromophore. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b908670f'> </P>