Extraction of photoexcited charge carriers transported up to 600 nanometers in CH 3 NH PbI could boost solar cell efficiency.

The thermal conductivities of beta-Ga2O3 single crystals along four different crystal directions were measured in the temperature range 80-495K using time domain thermoreflectance (TDTR) method. A large anisotropy was found. At room temperature, [010] direction has highest conductivity 27.0+/-2.0 W/mK, while that [100] lowest value 10.9+/-1.0 W/mK. high temperatures, follows a ~1/T relationship characteristic Umklapp phonon scattering, indicating phonon-dominated heat transport \b{eta}-Ga2O3...

Charge carrier diffusion coefficient and length are important physical parameters for semiconducting materials. Long-range in perovskite thin films has led to remarkable solar cell efficiencies; however, spatial temporal mechanisms of charge transport remain unclear. Here we present a direct measurement space time by mapping density with simultaneous ultrafast resolution ∼50-nm precision using transient absorption microscopy. These results directly visualize long-range ∼220 nm 2 ns...

Two-dimensional (2D) atomically thin perovskites with strongly bound excitons are highly promising for optoelectronic applications. However, the nature of nonradiative processes that limit photoluminescence (PL) efficiency remains elusive. Here, we present time-resolved and temperature-dependent PL studies to systematically address intrinsic exciton relaxation pathways in layered (C4H9NH3)2(CH3NH3)n−1PbnI3n+1 (n = 1, 2, 3) structures. Our results show scatterings via deformation potential by...

By systematically comparing experimental and theoretical transport properties, we identify the polar optical phonon scattering as dominant mechanism limiting electron mobility in beta-Ga2O3 to lower than 200 cm2/Vs at 300 K for donor doping densities 1018 cm-3. In spite of similar effective mass GaN, is 10x because a massive Frohlich interaction, due low energies stemming from crystal structure strong bond ionicity. Based on analysis, provide an empirical expression that should help...

Conventional wisdom tells us that interfacial thermal transport is more efficient when the interface adhesion energy enhanced. In this study, it demonstrated molecular bridges consisting of small molecules chemically absorbed on solid surfaces can enhance across hard–soft material interfaces by as much 7-fold despite a significant decrease in energy. This work provides an unconventional strategy to improve interfaces.

We present a systematic study of the roles crystallinity, interchain interaction, and exciton delocalization on ultrafast charge separation pathways in donor-acceptor copoloymer blends. characterize energy levels, excited state structures, dynamics species by combined spectroscopy computational quantum chemistry approaches. The alkyl side chain highly efficient copolymer for solar cell applications, PBDTTT...

Developing metal-organic frameworks (MOFs) with strong near-infrared II (NIR-II, 1000-1700 nm) emission is significant for biomedical research but highly challenging. So far there are no MOFs reported NIR-II imaging in vivo due to their poor efficiency. Herein, a strategy proposed prepare emission, by integrating NIR dye IR-3C and Ln

By direct imaging of singlet and triplet populations with ultrafast microscopy, it is shown that the diffusion length fission yield can be simultaneously optimized for tetracene its derivatives, making them ideal structures application in bilayer solar cells.

For optoelectronic devices based on polycrystalline semiconducting thin films, carrier transport across grain boundaries is an important process in defining efficiency. Here we employ transient absorption microscopy (TAM) to directly measure within and the hybrid organic–inorganic perovskite films for solar cell applications with 50 nm spatial precision 300 fs temporal resolution. By selectively imaging sub-bandgap states, our results show that lateral slowed down by these states at...

Long-range charge and exciton transport in quantum dot (QD) solids is a crucial challenge utilizing QDs for optoelectronic applications. Here, we present direct visualization of diffusion highly ordered CdSe superlattices by mapping population using ultrafast transient absorption microscopy. A temporal resolution ∼200 fs spatial precision ∼50 nm this technique provide assessment the upper limit QD solids. An length ∼125 has been visualized 3 ns experimental time window an coefficient (2.5 ±...

The efficiency of thermal transport across solid interfaces presents large challenges for modern technologies such as management electronics. In this paper, we report the first demonstration significant enhancement by introducing interfacial nanostructures. Analogous to fins that have been used macroscopic heat transfer in exchangers, nanopillar arrays patterned at interface help enlarged effective contact area. Such a benefit depends on geometry (e.g., pillar height and spacing), boundary...

Organic–inorganic lead halide perovskites have shown great promise in photovoltaics and optoelectronics. In these applications, device performance reliability can be strongly influenced by thermal transport the materials. Through laser pump–probe experiments, different microstructures of CH3NH3PbI3 perovskite thin films are found to give rise phonon scattering mechanism. The conductivity neat film decreases with temperature. Even though this agrees behavior its bulk crystalline counterparts,...

Side chain engineering of the conjugated polymer backbone improves its thermal conductivity.

We present an account of the optical properties Frenkel excitons in self-assembled porphyrin tubular aggregates that represent analog to natural photosynthetic antennae. Using a combination ultrafast spectroscopy and stochastic exciton modeling, we address both linear nonlinear absorption, relaxation pathways, role disorder. The static disorder-dominated absorption fluorescence line widths show little temperature dependence for lowest (Q band), which successfully simulate using model...

Impulsive solar energetic particle (SEP) events show substantial enhancements of heavy ions and 3He over the composition in Sun's atmosphere. Mass per charge dependent acceleration mechanisms have been proposed to account for this preferential acceleration. However, a problem emerged all models with measurement ionization states near 1 MeV nucleon−1, which showed that from C Mg are fully stripped, challenge had recognized early on. Since relied on differences charge-to-mass ratio enable...

Excited-state interactions between nanoscale cavities and photoactive molecules are critical in plasmonic nanolasing, although the underlying details less-resolved. This paper reports direct visualization of energy-transfer dynamics two-dimensional arrays gold bowtie nanocavities dye molecules. Transient absorption microscopy measurements single bowties within array surrounded by gain showed fast excited-state quenching (2.6 ± 1 ps) characteristic individual nanocavities. Upon optical...

In this work, we elucidate exciton structure, dynamics, and charge generation in the solution phase aggregates of a low-bandgap donor–acceptor polymer, poly(4,8-bis-alkyloxybenzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-alt-(alkylthieno[3,4-b]thiophene-2carboxylate)-2,6-diyl (PBDTTT). The polymer serve as precursors for thin film morphologies. We have identified intrachain interchain transitions resolved their relaxation pathways by comparing excitons to those isolated chains. Hot led stabilized...

The kinetics and pathway of electron transfer has been explored in a series reaction center mutants from Rhodobacter sphaeroides, which the leucine residue at M214 near bacteriopheophytin cofactor A-branch replaced with methionine, cysteine, alanine, glycine. These amino acids have substantially different volumes, both each other and, except for native leucine. Though mutation site is close to cofactor, involved transfer, none mutations alter composition primary charge separation essentially...