Point mutations in the seed sequence of miR-142-3p are present in a subset of acute myelogenous leukemia (AML) and in several subtypes of B-cell lymphoma. Here, we show that mutations associated with AML result both in loss of miR-142-3p function and in decreased miR-142-5p expression. loss altered the hematopoietic differentiation of multipotent hematopoietic progenitors, enhancing their myeloid potential while suppressing their lymphoid potential. During hematopoietic maturation, loss of increased ASH1L protein expression and consequently resulted in the aberrant maintenance of gene expression in myeloid-committed hematopoietic progenitors. loss also enhanced the disease-initiating activity of -mutant hematopoietic cells in mice. Together these data suggest a novel model in which miR-142, through repression of ASH1L activity, plays a key role in suppressing expression during normal myeloid differentiation. AML-associated loss-of-function mutations of disrupt this negative signaling pathway, resulting in sustained expression in myeloid progenitors/myeloblasts and ultimately contributing to leukemic transformation. These findings provide mechanistic insights into the role of miRNAs in leukemogenesis and hematopoietic stem cell function. .

Surface passivation of organic–inorganic halide perovskites (OIHPs) is a crucial step to annihilate the surface defects and to control the deteriorated ion migration phenomenon. Here, we study the role of lead sulfate (PbSO4) as an effective passivator in OIHP single crystals (SCs). Using impedance spectroscopy, we evaluate the ion migration and electrical properties of lead sulfate-passivated methylammonium lead tri-bromide (MAPbBr3) SCs. We found that the low-frequency impedance response that is assigned to the ionic motion in the MAPbBr3 SC is strongly affected by the inorganic PbSO4 surface treatment. The activation energy corresponding to the ion migration of MAPbBr3 SC is increased from 0.28 to 0.36 eV after PbSO4 surface treatment. The temperature-dependent I–V hysteresis of the MAPbBr3 SCs upon PbSO4 passivation was also measured. We found that such PbSO4 surface treatment stabilizes the crystal surface and improves the hysteresis properties of the crystals at elevated temperatures.

The last decade has witnessed the impressive progress of perovskite solar cells (PSCs), with power conversion efficiency exceeding 25%. Nevertheless, the unsatisfactory device stability and current–voltage hysteresis normally observed with most PSCs under operational conditions are bottlenecks that hamper their further commercialization. Understanding the electrical characteristics of the device during the aging process is important for the design and development of effective strategies for the fabrication of stable PSCs. Herein, electrochemical impedance spectroscopical (IS) analyses are used to study the time-dependent electrical characteristics of PSC. We demonstrate that both the dark and light ideality factors are sensitive to aging time, indicating the dominant existence of trap-assisted recombination in the investigated device. By analyzing the capacitance versus frequency responses, we show that the low-frequency capacitance increases with increasing aging time due to the accumulation of charges or ions at the interfaces. These results are correlated with the observed hysteresis during the current–voltage measurement and provide an in-depth understanding of the degradation mechanism of PSCs with aging time.

The growth of high-quality single-crystal (SC) perovskite films is a great strategy for the fabrication of defect-free perovskite solar cells (PSCs) with photovoltaic parameters close to the theoretical limit, which resulted in high efficiency and superior stability of the device. Plenty of growth methods for perovskite SCs are available to achieve a maximum power conversion efficiency (PCE) surpassing 21% for SC-based PSCs. However, there is still a lot of room to further push the efficiency by considering new crystal growth techniques, interface engineering, passivation approaches, and additive engineering. In this review, we summarize the recent progress in the growth of SC-based perovskite films for the fabrication of high-efficiency and stable PSCs. We describe the impact of SC growth of perovskite films and their quality on the device performance and stability, compared with the commonly used polycrystalline perovskite films. In the last section, the challenges and potential of SCs in PSCs are also covered for future development.

The lead-free Cs2AgBiBr6 double perovskites have recently emerged as promising candidates for optoelectronic applications due to their less toxicity and high stability. Although the photophysical study of Cs2AgBiBr6 has been extensively explored, the same for dielectric relaxation and carrier conduction remains elusive. Here, we uncover the dielectric relaxation and charge conduction mechanism in the Cs2AgBiBr6 single crystals using temperature-dependent electrochemical impedance spectroscopy in correlation with modulus spectroscopy. We found that the ionic displacement and space charge polarization are mainly responsible for the dielectric response. A sharp transition frequency as ∼191 Hz for 0 °C to ∼492 Hz for 90 °C was observed in the dielectric constant (ε′) versus temperature study, where dε′/dT exhibits a positive and negative coefficient below and above the transition frequency, respectively. Stevels model analysis suggests that the contribution of traps reduces with the increase in temperature and therefore conduction enhances. This model also confirms the polarons as the main conduction carriers in the Cs2AgBiBr6 semiconductor. The polaron hopping and binding energy were estimated as W H = 0.17 eV and E P = 0.34 eV, respectively. The binding energy of the polaron is larger than the room-temperature thermal energy, indicating the polaron hopping instead of free charge carrier transport as the dominant conduction mechanism. Furthermore, the imaginary part of -Z″ and M″ demonstrates the temperature-activated polaron relaxation from non-Debye type to Debye type process in Cs2AgBiBr6 crystals. Our study provides fundamental insights into the dielectric relaxation behavior needed for developing efficient dielectric switches and unveils the details of the carrier conduction mechanism in lead-free double perovskites.