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Electroluminescence efficiencies and stabilities of quasi-two-dimensional halide perovskites are restricted by the formation of multiple-quantum-well structures with broad and uncontrollable phase distributions. Here, we report a ligand design strategy to substantially suppress diffusion-limited phase disproportionation, thereby enabling better phase control. We demonstrate that extending the π-conjugation length and increasing the cross-sectional area of the ligand enables perovskite thin films with dramatically suppressed ion transport, narrowed phase distributions, reduced defect densities, and enhanced radiative recombination efficiencies. Consequently, we achieved efficient and stable deep-red light-emitting diodes with a peak external quantum efficiency of 26.3% (average 22.9% among 70 devices and cross-checked) and a half-life of ~220 and 2.8 h under a constant current density of 0.1 and 12 mA/cm2, respectively. Our devices also exhibit wide wavelength tunability and improved spectral and phase stability compared with existing perovskite light-emitting diodes. These discoveries provide critical insights into the molecular design and crystallization kinetics of low-dimensional perovskite semiconductors for light-emitting devices.

Surface passivation is an effective way to boost the efficiency and stability of perovskite solar cells (PSCs). However, a key challenge faced by most of the passivation strategies is reducing the interface charge recombination without imposing energy barriers to charge extraction. Here, a novel multifunctional semiconducting organic ammonium cationic interface modifier inserted between the light-harvesting perovskite film and the hole-transporting layer is reported. It is shown that the conjugated cations can directly extract holes from perovskite efficiently, and simultaneously reduce interface non-radiative recombination. Together with improved energy level alignment and the stabilized interface in the device, a triple-cation mixed-halide medium-bandgap PSC with an excellent power conversion efficiency of 22.06% (improved from 19.94%) and suppressed ion migration and halide phase segregation, which lead to a long-term operational stability, is demonstrated. This strategy provides a new practical method of interface engineering in PSCs toward improved efficiency and stability.

In admitting DNA sample taken at the crime scene in 2010 to compare it with a DNA sample taken from the defendant in 2020 courts assume that the defendant’s DNA has not changed in the prior ten years. This article questions that assumption using scientific findings published in the journals Scientific American and Science News.

In admitting DNA sample taken at the crime scene in 2010 to compare it with a DNA sample taken from the defendant in 2020 courts assume that the defendant’s DNA has not changed in the prior ten years. This article questions that assumption using scientific findings published in the journals Scientific American and Science News.

A list of hundreds of law review articles written by faculty members on the subject of "evidence"---narrowly defined to include only those topics covered by the Federal Rules of Evidence or its state clones. Readers who find their articles missing should notify the author who will add them to the next supplement.

Many writers have analyzed property interests in public spaces such as parking spots or lines of people waiting for an event. This paper considers the right to play on public basketball courts in a specific (but probably not unique) place: the basketball courts at U.C.L.A. In this instance the right to the place also includes a property interest in the game itself. This may interest those who study other cooperative endeavors.

Many people find electoral politics dissatisfying. This short collection of axioms offers some reasons why such dissatisfaction seems inevitable. Astute readers may infer from this that participation in civil society provides a useful supplement to casting a vote as a means to produce desired change.

Ever since the majority of the Supreme Court, in Crawford v. Washington took the power to determine the reliability of hearsay statements out of the hands of judges and transferred it to the jury, prosecutors and their allies have tried to chip away at Crawford---even asking the Court to overrule Crawford. In 2011, in Michigan v. Bryant, five Harvard elitists gave the prosecutors what wanted they wanted, surreptitiously overruling Crawford. This article takes a first crack at unpacking the thirteen-factor Bryant test. Using the opinions of the majority and Justice Scalia’s outraged dissent, as well as the briefs and oral argument, it addresses a few of the issues that lower courts will face in attempting to make sense of a decision that rests more on bogus history and (as Justice Scalia says) the personal preferences of the judges than on any historically-sound policy.

Water management within vulnerable ecosystems managed by multiple jurisdictions can be very complex. This study compares regulatory environments and deconstructs the approaches used for watershed governance and environmental management inside two UNESCO’s Biosphere Reserves to identify possible transferability between the two management entities. Three methodological approaches were applied: participatory observation, in-depth interviews of key informants, and document research. We concluded that while there are differences between the regulatory frameworks and localized practices, at a foundational level the goals and desired outcomes relating to environmental protection are not dependent on location, but mainly on the integration and the establishment of common objectives among the diverse social actors involved in the management and from the interaction between different organisms of social control. Additionally, there are elements in the application of regulations and practices in both locales that could be transferred to other jurisdictions interested in addressing watershed protection in vulnerable ecosystems governed by multiple jurisdictions.

In the well-known Crawford decision, the United States Supreme Court severed the relationship between the hearsay rule and the right of confrontation by limiting the scope of the Confrontation Clause of the Sixth Amendment to "testimonial" statements. In subsequent decision, the Court appeared to retreat from this anti-fusionist stance. In 2009 in Massacusetts v. Melendez-Diaz the majority opinion restated and strengthened the revolution promised by Crawford. This essay, which will appear sometime in 2010 as § 6371.4 of 30A Wright and Graham, Federal Practice and Procedure: Evidence (Supplement 2010) analyzes the Melendez-Diaz majority opinion in light of the briefs, the oral argument, and the fallout from the Court's prior confrontation decisions.

Evidence teachers, and other law professors, often make instrumental arguments. This short [9 paragraphs] feuilleton speculates about a strange gap in instrumental analysis---the reluctance to confront the values upon which such arguments rest. It offers no answers but a least it has no footnotes and may spark thought in others who do have the answer.

In 2004 in Crawford v. Washington, 511 U.S. 36, 124 S.Ct. 1354, 158 L.Ed.2d 177, the U.S. Supreme Court sought to undo the fusion between the Sixth Amendment right of confrontation and evidentiary rule of hearsay epitomized by its 1980 decision in Ohio v. Roberts, 448 U.S. 56, 100 S.Ct. 2531, 65 L.Ed.2d 597. Crawford reduced the scope of the right of confrontation but made it far more rigorous than it had been under Roberts.However, the majority opinion in Crawford tried to downplay the decision’s revolutionary potential and to emphasize its continuity with the Supreme Court’s prior cases. This left the state and lower federal courts understandably puzzled about just what to make of Crawford. See Crawford Interpreted: 2004-2005, available at: http://repositories.cdlib.org/uclalaw/plltwps/5-23So two years later in Davis v. Washington, 2006, 547 U.S. ___, 126 S.Ct. 2266, the Court returned to Crawford by reviewing a pair of domestic violence cases from Washington and Indiana that typified the way in which state courts tried to narrow the impact of Crawford. Unlike Crawford, Davis was a quite modest opinion that rejected two categorical exceptions to Crawford for 911 calls and so-called “investigatory interrogations---and explicitly overruled Roberts. See The Revolution Revised: A Guided Tour of Davis v. Washington, available at http://repositories.cdlib.org/uclalaw/plltwps/6-07However, the modest scope of Davis is difficult to appreciate without some sense of the range of problems with which the state and lower federal courts grappled in the first two years under Crawford. Accordingly, this essay comprehensively collects and attempts to synthesize the hundreds of cases decided down to the eve of Davis. Since “unpublished opinion” has become a nearly complete oxymoron, “unpublished”, “depublished”, and otherwise non-precedential opinions are included on the theory that users may find them helpful even if they cannot cite them.Note on citation form. Since this essay will eventually appear in the 2007 pocket parts as § 6371.2 of 30A Wright & Graham, Federal Practice and Procedure: Evidence, it adheres to the idiosyncratic citation form of that treatise. For example, citations to that treatise appear as simply “FPP § 6370, text at notecall 120.” Readers who want to find what is said at that point may go on Westlaw, enter “FPP § 6370” in the “Find” box, and hit “go.”

[In Crawford v. Washington, 541 U.S. 36, 124 S.Ct. 1354, 158 L.Ed.2d 177 (2004) the U.S. Supreme Court radically altered its approach to application of the Sixth Amendment right of confrontation to evidentiary use of hearsay statements. Lower courts then began to pick-and-choose among the three “formulations” of those “testimonial” statements the Court had offered and some interpreted Crawford to allow categori-cal exceptions to the right of confrontation. See Wright & Graham, Federal Practice and Procedure Evidence § 6371.2 (Supp.2006)[cited in this essay as “FPP” as it can be found on Westlaw by entering those letters and the section number desired.]In Davis v. Washington, 541 U.S. ___, 126 S.Ct. 2266 (2006) the Supreme Court reviewed decisions involving two of the categorical exceptions; 911 calls and “investiga-tory interrogations.” In a self-consciously narrow opinion by Justice Scalia, eight members of the Court rejected per se treatment of those categories and apparently overruled Ohio v. Roberts, 448 U.S. 56, 100 S.Ct. 2531, 65 L.Ed.2d 597 (1980). But despite its narrow scope, the Davis opinion has implications for the Crawford “formulations” and two proposed alternatives, for the future of categorical analysis, and for the Court’s reading of the history and policy of the Confrontation Clause. This essay examines all of these.]

In 2004, the Supreme Court redid once again its interpretation of the Confrontation Clause of the Sixth Amendment. The majority opinion by Justice Scalia created a dual track system for applying the right of confrontation to hearsay evidence. The first track subjected evidence the opinion called “testimonial” to a severe standard; the evidence was inadmissible unless the declarant was unavailable and the defendant had a prior opportunity to cross-examine the declarant. Non-”testimonial” evidence ran down the other track to an uncertain destination. The author has argued elsewhere [ see forthcoming article at http://repositories.cdlib.org/uclalaw/plltwps/5-10 ] that the Court might have found some support for a dual-track right of confrontation in the history of the Confrontation Clause where the Founders drew a distinction between “accusers” and “witnesses.”The present essay documents the interpretation of Crawford by state and lower federal courts in the year after the Supreme Court’s decision. The author believes these cases suggest that when the Supreme Court revisits Crawford, it might limit that case to hearsay that amounts to an “accusation” in common parlance. Moreover, in dealing with accusations and non-accusatorial hearsay, the Court would do well to consider the Confrontation Clause, not as an isolated provision of the Sixth Amendment, but as a part of a “holistic” Bill of Rights that captures what the Founders called “trial by jury” when they objected to the use of inquisitorial criminal procedures.

Some scholars want to codify the federal law of privilege but the history of the many governmental privileges suggests that converting common law privileges to statutory form may not do much to reform privilege law. After restating the conventional view of privileges, the author argues that both Congress and the courts can claim legitimate power to control them. He next outlines the political economy of the government secrecy that the privileges aim to protect and provides an econometric model to explain why our socio-political structure fosters bureaucratic secrecy. The author then uses the notorious “Quackgate” case [Cheney v. U.S.District Court, 124 S.Ct. 2576 (2004)] to illustrate how the secrecy-privilege system operates. The article concludes with thumbnail sketches of privilege cases to show that neither Congress nor the courts have the will to restrict government demands for privileged secrecy.

In Crawford v. Washington, the Supreme Court tried again to reformulate the restrictions of the Confrontation Clause of the Sixth Amendment on the admissibility of hearsay evidence offered by prosecutors. Crawford adopted a dual system of analysis, with a more stringent test for an ill-defined class of statements the Court called “testimonial” while leaving other hearsay statements to the permissive standards laid down in Ohio v. Roberts. Justice Scalia’s majority opinion relies upon a conventional version of history to justify its new scheme. This essay argues that the conventional history errs in supposing that the right of confrontation originated in England. The “true history” supports some parts of the Crawford analysis but undermines the Court’s narrow view that conflates confrontation and cross-examination.