Since 2011, the art of the Arab uprisings has been the subject of much scholarly and popular attention. Yet the role of artists, writers and filmmakers themselves as social actors working under ...extraordinary conditions has been relatively neglected. Drawing on critical readings of Bourdieu’s Field Theory, this book explores the production of culture in Arab social spaces in ‘crisis’. In ten case studies, contributors examine a wide range of countries and conflicts, from Algeria to the Arab countries of the Gulf. They discuss among other things the impact of Western public diplomacy organisations on the arts scene in post-revolutionary Cairo and the consequences of dwindling state support for literary production in Yemen. Providing a valuable source of empirical data for researchers, the book breaks new ground in adapting Bourdieu’s theory to the particularities of cultural production in the Middle East and North Africa.
Organic–inorganic perovskites are well suited for optoelectronic applications. In particular, perovskite single and perovskite tandem solar cells with silicon are close to their market entry. Despite ...their swift rise in efficiency to more than 21%, solar cell lifetimes are way below the needed 25 years. In fact, comparison of the time when the device performance has degraded to 80% of its initial value (T80 lifetime) of numerous solar cells throughout the literature reveals a strongly reduced stability under illumination. Herein, the various detrimental effects are discussed. Most notably, moisture‐ and heat‐related degradation can be mitigated easily by now. Recently, however, several photoinduced degradation mechanisms have been observed. Under illumination, mixed perovskites tend to phase segregate, while, further, oxygen catalyzes deprotonation of the organic cations. Additionally, during illumination photogenerated charge can be trapped in the NH antibonding orbitals causing dissociation of the organic cation. On the other hand, organic–inorganic perovskites exhibit a high radiation hardness that is superior to crystalline silicon. Here, the proposed degradation mechanisms reported in the literature are thoroughly reviewed and the microscopic mechanisms and their implications for solar cells are discussed.
T80 lifetimes of organic–inorganic perovskite solar cells are strongly reduced under illumination. Various degradation mechanisms are therefore discussed throughout the literature. Degradation by moisture or heat is well understood and mitigation possible. Photoinduced phase segregation and photoinduced dissociation of the organic cation, however, remain unsolved. Recent observations enlighten the underlying microscopic mechanisms and may pave the way for stable perovskites.
With a recent surge of research on narcissism, narcissism questionnaires are increasingly being translated and applied in various countries. The measurement invariance of an instrument across ...countries is a precondition for being able to compare scores across countries. We investigated the cross-cultural measurement invariance of three narcissism questionnaires (Brief Pathological Narcissism Inventory B-PNI, Narcissistic Personality Inventory NPI, and Narcissistic Admiration and Rivalry Questionnaire NARQ) and mean-level differences across samples from the United States (N = 2,464), the United Kingdom (N = 307), and Germany (N = 925). Overall, the B-PNI and NARQ functioned equivalently for the U.S. and U.K. participants. More violations of measurement invariance were found between Germany and the combined U.S. and U.K. samples, and for the NPI. In the B-PNI and NARQ, Americans scored higher than individuals from the United Kingdom regarding agentic aspects (self-sacrificing self-enhancement, admiration), while Germans scored lower than both Americans and U.K. individuals regarding antagonistic (entitlement rage, rivalry) and neurotic (hiding the self, contingent self-esteem) aspects. More inconsistent results were found for NPI facets. When noninvariance was present, observed means yielded biased results. Thus, the degree of measurement invariance across translated instrument versions should be considered in cross-cultural comparisons, even with culturally similar countries.
Tandem solar cells combining silicon and perovskite absorbers have the potential to outperform state-of-the-art high efficiency silicon single junction devices. However, the practical fabrication of ...monolithic silicon/perovskite tandem solar cells is challenging as material properties and processing requirements such as temperature restrict the device design. Here, we fabricate an 18% efficient monolithic tandem cell formed by a silicon heterojunction bottom- and a perovskite top-cell enabling a very high open circuit voltage of 1.78 V. The monolithic integration was realized vialow temperature processing of the semitransparent perovskite sub-cell where an energetically aligned electron selective contact was fabricated by atomic layer deposition of tin oxide. The hole selective, transparent top contact was formed by a stack of the organic hole transport material spiro-OMeTAD, molybdenum oxide and sputtered indium tin oxide. The tandem cell design is currently limited by the photocurrent generated in the silicon bottom cell that is reduced due to reflectance losses. Based on optical modelling and first experiments, we show that these losses can be significantly reduced by combining optical optimization of the device architecture including light trapping approaches.
The radiation hardness of CH3NH3PbI3‐based solar cells is evaluated from in situ measurements during high‐energy proton irradiation. These organic–inorganic perovskites exhibit radiation hardness and ...withstand proton doses that exceed the damage threshold of crystalline silicon by almost 3 orders of magnitude. Moreover, after termination of the proton irradiation, a self‐healing process of the solar cells commences.
Perovskite semiconductors are an attractive option to overcome the limitations of established silicon based photovoltaic (PV) technologies due to their exceptional opto‐electronic properties and ...their successful integration into multijunction cells. However, the performance of single‐ and multijunction cells is largely limited by significant nonradiative recombination at the perovskite/organic electron transport layer junctions. In this work, the cause of interfacial recombination at the perovskite/C60 interface is revealed via a combination of photoluminescence, photoelectron spectroscopy, and first‐principle numerical simulations. It is found that the most significant contribution to the total C60‐induced recombination loss occurs within the first monolayer of C60, rather than in the bulk of C60 or at the perovskite surface. The experiments show that the C60 molecules act as deep trap states when in direct contact with the perovskite. It is further demonstrated that by reducing the surface coverage of C60, the radiative efficiency of the bare perovskite layer can be retained. The findings of this work pave the way toward overcoming one of the most critical remaining performance losses in perovskite solar cells.
Nonradiative recombination induced by C60 is limiting the performance of pin type perovskite solar cells and remains poorly understood. In this manuscript, the possible recombination pathways are systematically examined and it is discovered that across‐interface recombination dominates. A point contact strategy is suggested to circumvent the loss, paving the way to improved pin type perovskite solar cells.
Abstract
Inverted perovskite solar cells still suffer from significant non-radiative recombination losses at the perovskite surface and across the perovskite/C
60
interface, limiting the future ...development of perovskite-based single- and multi-junction photovoltaics. Therefore, more effective inter- or transport layers are urgently required. To tackle these recombination losses, we introduce ortho-carborane as an interlayer material that has a spherical molecular structure and a three-dimensional aromaticity. Based on a variety of experimental techniques, we show that ortho-carborane decorated with phenylamino groups effectively passivates the perovskite surface and essentially eliminates the non-radiative recombination loss across the perovskite/C
60
interface with high thermal stability. We further demonstrate the potential of carborane as an electron transport material, facilitating electron extraction while blocking holes from the interface. The resulting inverted perovskite solar cells deliver a power conversion efficiency of over 23% with a low non-radiative voltage loss of 110 mV, and retain >97% of the initial efficiency after 400 h of maximum power point tracking. Overall, the designed carborane based interlayer simultaneously enables passivation, electron-transport and hole-blocking and paves the way toward more efficient and stable perovskite solar cells.
Highly efficient perovskite based solar cells have the potential to be a game-changing solar array technology for space applications that can be flexible, truly roll-able, ultra-lightweight and ...highly stowable. Outside earth's magnetic field, however, ionizing radiation causes localized defect states that accumulate and ultimately cause the failure of electronic devices. This study, assesses the radiation hardness of the widely used triple cation based perovskite absorber material, namely Cs
0.05
MA
0.17
FA
0.83
Pb(I
0.83
Br
0.17
)
3
employing 20 and 68 MeV proton irradiation. Therefore,
in situ
measurements of the degradation of the proton induced current as well as the photovoltaic performance during proton irradiation are used as two independent metrics. Both measurements suggest that triple cation perovskites even exceed the radiation hardness of SiC, which is a material often proposed to possess an excellent radiation hardness. Our optimized Cs
0.05
MA
0.17
FA
0.83
Pb(I
0.83
Br
0.17
)
3
based space solar cells reach efficiencies of 18.8% under AM0 illumination and maintain 95% of their initial efficiency even after irradiation with protons at an energy 68 MeV and a total dose of 10
12
p per cm
2
. Degradation under 20 MeV proton irradiation is even lower. Despite the negligible impact on solar cell device performance, this study identifies that proton irradiation is changing the recombination kinetics under low excitation densities profoundly. Dark capacitance-voltage and current-voltage characteristics, photoluminescence spectra as well as photoluminescence and
V
oc
decays are analyzed in depth. Surprisingly, two fold prolonged PL and
V
oc
decay times are observed after proton irradiation. Often, such prolongations are attributed to a reduced charge recombination. Our kinetic model, precisely describing the observed time evolution after photoexcitation, however, establishes the prolonged release of trapped minority charge carriers from proton-radiation induced trap states.
Although highly energetic proton irradiation forms localized trap states in triple cation perovskites, solar cells possess exceptional radiation hardness.
Aim of this project was to assess occupational biological hazards with regard to the risk of hepatitis A (HAV) and hepatitis B (HBV) and the need for occupational health care in schools for pupils ...with special needs. Teachers and educational specialists were surveyed about activities potentially providing exposure to biological agents and their individual immune status regarding HAV and HBV by a detailed questionnaire. Descriptive analyses, group comparisons and logistic regression were performed to identify factors influencing the HAV and HBV immune status. 1398 teachers and educational specialists took part. 1381 respondents reported having physical contact with pupils at work (98%). Daily contact was reported by up to 84% of all employees. Being scratched, bitten or spat at was reported by up to 93%. Hazardous activities are performed by both teachers and educational specialists. The vaccination rate was reported to be 58% for HAV and 64% for HBV. In regression analyses, failing to receive vaccine counselling HAV: aOR 0.36 (95% CI 0.28; 0.46; p < 0.001), HBV: aOR 0.43 (95% CI 0.33; 0.55; p < 0.001) or non-participation in infection prevention instruction HBV: aOR 0.54 (95% CI 0.39; 0.75; p < 0.001) were found to be significant predictors of low vaccination rates. Employees who are at risk due to occupational exposure should be instructed about infection prevention and vaccination against HAV and HBV.
Efficient mixed metal lead‐tin halide perovskites are essential for the development of all‐perovskite tandem solar cells, however they are currently limited by significant short‐circuit current ...losses despite their near optimal bandgap (≈1.25 eV). Herein, the origin of these losses is investigated, using a combination of voltage dependent photoluminescence (PL) timeseries and various charge extraction measurements. It is demonstrated that the Pb/Sn‐perovskite devices suffer from a reduction in the charge extraction efficiency within the first few seconds of operation, which leads to a loss in current and lower maximum power output. In addition, the emitted PL from the device rises on the exact same timescales due to the accumulation of electronic charges in the active layer. Using transient charge extraction measurements, it is shown that these observations cannot be explained by doping‐induced electronic charges but by the movement of mobile ions toward the perovskite/transport layer interfaces, which inhibits charge extraction due to band flattening. Finally, these findings are generalized to lead‐based perovskites, showing that the loss mechanism is universal. This elucidates the negative role mobile ions play in perovskite solar cells and paves a path toward understanding and mitigating a key loss mechanism.
Current losses in perovskite solar cells (PSCs) are investigated using transient photoluminescence and charge extraction measurements. Mobile ions cause a substantial current and efficiency loss by accumulating at the perovskite/transport layer interfaces, which screens the internal electric field. This work elucidates the detrimental impact of mobile ions in PSCs and paves the path toward mitigating this key loss mechanism.
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