We demonstrate open-circuit voltages exceeding 1.26 V for CH3NH3PbI3 solar cells by careful process optimization of the perovskite and its interfaces to the electron and hole transport layers. This open-circuit voltage is the highest reported so far in a full MAPI cell stack and only 64 mV below the maximum open circuit voltage that is possible for this material. We confirm these values for the open circuit voltage by independent measurements of the external photoluminescence quantum efficiency reaching values of 5 % for the fully processed solar cell. We further find exceptionally long photoluminescence lifetimes in full cells and in layer stacks involving one or two contact layers. Numerical simulations reveal that these long photoluminescence lifetimes are only possible with extremely low interface recombination velocities between absorber and contact materials.

leads to reduced open-circuit voltages and efficiencies at a given illumination condition. [6][7][8][9][10] Transient photoluminescence (TPL) is a frequently used tool to monitor the charge-carrier dynamics and investigate these recombination losses. [11][12][13] While TPL measured on bare semiconductor films on glass is a well-understood and frequently used method to derive charge-carrier lifetimes and recombination coefficients in halide perovskites and other semiconductors, [14][15][16][17][18] it is typically the recombination at interfaces between the absorber and charge transfer layers that is the dominant source of recombination in a complete perovskite device. [19][20][21][22][23][24][25] However, adding contact layers to the perovskite film not only adds additional recombination paths but also leads to effects like charge-carrier separation or interfacecharging effects [25][26][27] that may change the recombination kinetics fundamentally. Thus, the information on recombination may be totally obscured by interfacial effects such that, e.g., a faster photoluminescence (PL) decay cannot anymore be interpreted simply as an increased recombination coefficient. Hence, misinterpretation of experimental data becomes likely, especially if the information contained in the decay curve is reduced to a single value-the characteristic decay time of a monoexponential decay. The present paper introduces a method to analyze the differential PL decay that uses the derivative of the photoluminescence at every time during the transient. [26,28] We propose to plot this decay time as a function of the corresponding quasi-Fermilevel splitting allowing us to better understand the complex interplay between charge extraction and interface or contact charging with radiative and non-radiative recombination. We use a combination of numerical simulations with Sentauraus TCAD, analytical models, and experimental data to illustrate how the different effects influence the PL transients and the resulting decay times.In the following, we investigate transient photoluminescence measurements on the different sample geometries shown in the overview in Figure 1 that start with films on glass and continue via layer stacks to full devices and discuss their respective peculiarities. We show how the addition of further layers and interfaces modifies the transients and adds physical effects that must be considered. With this step-by-step description, we aim to create an understanding of which processes dominate and are important for these different sample types and how they affect the transient PL decay and the extracted decay time. This step-by-step approach is conceptually similar to the already While transient photoluminescence (TPL) measurements are a very popular tool to monitor the charge-carrier dynamics in the field of halide perovskite photovoltaics, interpretation of data obtained on multilayer samples is highly challenging due to the superposition of various effects that modulate the charge-carrier concentration in the perovskite layer ...

Despite remarkable advances in the genomic characterization of adult melanoma, the molecular pathogenesis of pediatric melanoma remains largely unknown. We analyzed 15 conventional melanomas (CMs), 3 melanomas arising in congenital nevi (CNMs), and 5 spitzoid melanomas (SMs), using various platforms, including whole genome or exome sequencing, the molecular inversion probe assay, and/or targeted sequencing. CMs demonstrated a high burden of somatic single-nucleotide variations (SNVs), with each case containing a TERT promoter (TERT-p) mutation, 13/15 containing an activating BRAF V600 mutation, and >80% of the identified SNVs consistent with UV damage. In contrast, the three CNMs contained an activating NRAS Q61 mutation and no TERT-p mutations. SMs were characterized by chromosomal rearrangements resulting in activated kinase signaling in 40%, and an absence of TERT-p mutations, except for the one SM that succumbed to hematogenous metastasis. We conclude that pediatric CM has a very similar UV-induced mutational spectrum to that found in the adult counterpart, emphasizing the need to promote sun protection practices in early life and to improve access to therapeutic agents being explored in adults in young patients. In contrast, the pathogenesis of CNM appears to be distinct. TERT-p mutations may identify the rare subset of spitzoid melanocytic lesions prone to disseminate.