Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Device Characteristics of CZTSSe Thin‐Film Solar Cells with 12.6% Efficiency

The large photocurrent hysteresis observed in many organometal trihalide perovskite solar cells has become a major hindrance impairing the ultimate performance and stability of these devices, while its origin was unknown. Here we demonstrate the trap states on the surface and grain boundaries of the perovskite materials to be the origin of photocurrent hysteresis and that the fullerene layers deposited on perovskites can effectively passivate these charge trap states and eliminate the notorious photocurrent hysteresis. Fullerenes deposited on the top of the perovskites reduce the trap density by two orders of magnitude and double the power conversion efficiency of CH(3)NH(3)PbI(3) solar cells. The elucidation of the origin of photocurrent hysteresis and its elimination by trap passivation in perovskite solar cells provides important directions for future enhancements to device efficiency.

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Origin and elimination of photocurrent hysteresis by fullerene passivation in CH3NH3PbI3 planar heterojunction solar cells

In this contribution, we present a new certified world record efficiency of 20.1 and 20.3% for Cu(In,Ga)Se2 thin-film solar cells. We analyse the characteristics of solar cells on such a performance level and demonstrate a high degree of reproducibility. Copyright © 2011 John Wiley & Sons, Ltd.

New world record efficiency for Cu(In,Ga)Se2 thin‐film solar cells beyond 20%

The ionic defects at the surfaces and grain boundaries of organic–inorganic halide perovskite films are detrimental to both the efficiency and stability of perovskite solar cells. Here, we show that quaternary ammonium halides can effectively passivate ionic defects in several different types of hybrid perovskite with their negative- and positive-charged components. The efficient defect passivation reduces the charge trap density and elongates the carrier recombination lifetime, which is supported by density-function-theory calculation. The defect passivation reduces the open-circuit-voltage deficit of the p–i–n-structured device to 0.39 V, and boosts the efficiency to a certified value of 20.59 ± 0.45%. Moreover, the defect healing also significantly enhances the stability of films in ambient conditions. Our findings provide an avenue for defect passivation to further improve both the efficiency and stability of solar cells. Losses in solar cells can be caused by material defects in the bulk or at interfaces. Here, Zheng et al. use quaternary ammonium halides to passivate various perovskite absorbers and prepare solar cells with certified efficiency above 20%, suggesting that both anionic and cation defects are affected.

https://par.nsf.gov/servlets/purl/10056130

Defect passivation in hybrid perovskite solar cells using quaternary ammonium halide anions and cations

A method to deduce energy distributions of defects in the band gap of a semiconductor by measuring the complex admittance of a junction is proposed. It consists of calculating the derivative of the junction capacitance with respect to the angular frequency of the ac signal corrected by a factor taking into account the band bending and the drop of the ac signal over the space charge region of the junction. Numerical modeling demonstrates that defect distributions in energy can be reconstructed by this method with high accuracy. Defect distributions of polycrystalline Cu(In,Ga)Se2 thin films are determined by this method from temperature dependent admittance measurements on heterojunctions of Cu(In,Ga)Se2 with ZnO that are used as efficient thin film solar cells.

Determination of defect distributions from admittance measurements and application to Cu(In,Ga)Se2 based heterojunctions

Cu2ZnSnS4 thin film solar cells from electroplated precursors: Novel low-cost perspective

In this paper the Sn loss from thin films of the material system Cu–Zn–Sn–S and the subsystems Cu–Sn–S and Sn–S in high vacuum is investigated. A combination of in situ x-ray diffractometry and x-ray fluorescence (XRF) at a synchrotron light source allowed identifying phases, which tend to decompose and evaporate a Sn-containing compound. On the basis of the XRF results a quantification of the Sn loss from the films during annealing experiments is presented. It can be shown that the evaporation rate from the different phases decreases according to the order SnS→Cu2SnS3→Cu4SnS4→Cu2ZnSnS4. The phase SnS is assigned as the evaporating compound. The influence of an additional inert gas component on the Sn loss and on the formation of Cu2ZnSnS4 thin films is discussed.

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On the Sn loss from thin films of the material system Cu-Zn-Sn-S in high vacuum

This article presents a systematic study on the electronic transport mechanisms of CuGaSe2-based thin film solar cells. A variety of samples with different types of stoichiometry deviations, substrates and buffer layers is investigated. We propose two transport models, namely tunneling enhanced volume recombination and tunneling enhanced interface recombination, which allow to explain the observed features for all devices under consideration. The doping level of the absorber layer turns out to be the most decisive parameter for the electronic loss mechanism. The doping is influenced by the type of stoichiometry deviation as well as by the Na content of the substrate. High doping levels result in tunnel assisted recombination. The best solar cells display the lowest tunneling rates. For these devices treatments of the absorber surface by air-annealing and/or the deposition temperature of the CdS buffer layer are decisive for the final device performance. We use the investigation of the open-circuit voltage...

H.-W. Schock

Papers

Determination of defect distributions from admittance measurements and application to Cu(In,Ga)Se2 based heterojunctions

Cu2ZnSnS4 thin film solar cells from electroplated precursors: Novel low-cost perspective

On the Sn loss from thin films of the material system Cu-Zn-Sn-S in high vacuum

Electronic properties of CuGaSe2-based heterojunction solar cells. Part I. Transport analysis

Influence of sodium on the growth of polycrystalline Cu(In,Ga)Se2 thin films