Occurrence Of Hole Research Articles

Recent progress in surface modification and interfacial engineering for high-performance perovskite light-emitting diodes

Perovskite-based light-emitting diodes (PeLEDs) are an emerging lighting and display due to their extraordinarily photoelectric characteristics. In the past few years, external quantum efficiency (EQE) has enhanced from less than 0.1% to over 20%, which is comparable to that of conventional organic light-emitting diodes. As a result of low production cost and high energy efficiency of perovskite materials, PeLEDs have attracted enormous attention. However, in the cost-efficient solution-based process, the perovskite film with the occurrence of electron and hole traps as well as the rough surface are unfavorable for the PeLEDs. Surface modification and interfacial engineering play a significant role in the performance of light-emitting devices. Various strategies for the improvement of surface morphology have been executed to solve intrinsic challenges related to PeLEDs. In this review, recent advances in the morphology engineering of PeLEDs are summarized. Compositional engineering, additive engineering, annealing treatment, humidity management, solvent control, gas-quenching and vapor-assisted method, as well as interlayer engineering and self-assembly monolayer, are specifically discussed; additionally, an outlook is addressed that will provide inspiration for further enhancing the performances of PeLEDs. • The latest development in PeLED based on surface modification and interfacial engineering is reviewed. • The effects of surface modification and interfacial engineering are comprehensively summarized. • Challenges, perspectives and future directions in the field of perovskite light-emitting diodes are provided.

Origins of Structural Hole Traps in Hydrogenated Amorphous Silicon

The inherently disordered nature of hydrogenated amorphous silicon (a-Si:H) obscures the influence of atomic features on the trapping of holes. To address this, we have created a set of over two thousand ab initio structures of a-Si:H and explored the influence of geometric factors on the occurrence of deep hole traps using density-functional theory. Statistical analysis of the relative contribution of various structures to the trap distribution shows that floating bonds and ionization-induced displacements correlate most strongly with hole traps in our ensemble.

EXTREME HOST GALAXY GROWTH IN POWERFUL EARLY-EPOCH RADIO GALAXIES

During the first half of the universe's age, a heyday of star-formation must have occurred because many massive galaxies are in place after that epoch in cosmic history. Our observations with the revolutionary Herschel Space Observatory reveal vigorous optically obscured star-formation in the ultra-massive hosts of many powerful high-redshift 3C quasars and radio galaxies. This symbiotic occurrence of star-formation and black hole driven activity is in marked contrast to recent results dealing with Herschel observations of X-ray selected active galaxies. Three archetypal radio galaxies, at redshifts 1.132,1.575, and 2.474 are presented here, with inferred star-formation rates of hundreds of solar masses per year. A series of spectacular coeval AGN/starburst events may have formed these ultra-massive galaxies and their massive central black holes during their relatively short lifetimes.

FAMILIAL TRENDS IN A POPULATION WITH MACULAR HOLES

To determine if patients with macular hole report an increased family history of macular hole compared with control patients and compare the report of family history between patients with unilateral and bilateral macular holes. This was a multicenter case-control study. Charts of patients coded with diagnosis of macular hole were reviewed, and the diagnosis of idiopathic full-thickness macular hole was ascertained in 166 patients. The control group comprised 136 patients without macular hole or trauma who presented with senile cataract. Family history was obtained from all patients through a telephone interview. Six of 166 (3.6%) macular hole patients surveyed reported a history of macular hole in a primary relative compared with none of 136 (0.0%) control patients (odds ratio is infinity, with 95% confidence interval 1.295 to infinity); however, this finding may be explained by confounders such as age and number of family members. Two of the 142 (1.4%) patients with unilateral holes versus 4 of the 24 (16.7%) patients with bilateral holes reported a family history (odds ratio is 0.0714, with 95% confidence interval 0.0063 to 0.5537), and this finding remains significant when logistic regression is performed to evaluate variables of age and number of family members as potential confounders. There is an increased report of familial occurrence of macular hole in patients with macular holes compared with control patients; however, logistic regression relates this finding to variables of age and number of family members. Patients with bilateral macular holes are more likely to report a family history of macular hole than patients with unilateral macular holes, and this finding remains significant in the presence of age and number of family members. These findings may suggest a familial component to macular hole.

Effects of hole and electron trapping on organic field-effect transistor transfer characteristic

Routine organic field-effect transistor measurements are performed at negative and positive gate voltages leading to the occurrence of both hole and electron trapping. Despite this fact, the big majority of studies have focused either on hole trapping or on electron trapping but not on both at the same time. This paper presents the influences of trapped electron concentration n trap and trapped hole concentration p trap on the transfer characteristic (TC) features: onset voltage, hysteresis and transconductance, i.e. apparent mobility. Some effects are common to both charge types: (1) hysteresis is due to a combination of lower detrapping rate than sweep rate for n trap and p trap , (2) the transconductance is decreased by the super-linear V G dependence of p trap and by n trap detrapping. One effect is opposite to both charge types: p trap ( n trap ) shifts the onset voltage towards negative (positive) value. We consider that the knowledge of trap-induced effects from both charge types is useful for correctly interpreting and understanding TCs.

Bilateral macular holes in X-linked retinoschisis: Now the spectrum is wider

Bilateral occurrence of macular hole in X-linked retinoschisis is an extremely rare event. Spectral domain optical coherence tomography (OCT) findings revealed that formation of a macular hole is secondary to the retinoschisis process alone. Bilateral macular holes should be added to the spectrum of X-linked retinoschisis variations and the retinoschisis process alone should be accounted for their formation.