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Abstract MAPbI3 is the most attractive perovskite, but toxicity and instability issues hinder its commercial applications. Stability can be improved by halide mixing; however, Pb‐free perovskites are designed to alleviate the toxicity and to enable green photovoltaics (PVs). To this end, MAPbI3‐xClx, FASnI3‐xClx and CsSbCl4 films are deposited by spay pyrolysis technique in atmospheric conditions. SEM images demonstrated that through this process, high quality film fabrication is possible. Color of the precursor solutions changes with stirring time. High crystallinity and existence of mixed‐phases are confirmed by XRD analysis. Compositions greatly impact the morphology and optical properties. Value of α is larger than 105 cm−1 for all films. Band gaps of FASnI3‐xClx and CsSbCl4 are 1.46 eV and 1.52 eV, which are more suitable for PVs, optoelectronic applications than MAPbI3‐xClx (Eg = 1.59 eV). The efficiency was obtained as 16.34%, 9.90%, and 13.08% for deposited MAPbI3‐xClx, FASnI3‐xClx, and CsSbCl4 films. The lower efficiency can further be enhanced by optimizing parameters, and in this study it was found as 20.78%, 11.93%, and 18.02%. Theoretical calculations show the films can easily produce O2 by a strong oxidation process. Thus, the favorable characteristics of FASnI3‐xClx and CsSbCl4 make alternative Pb‐free perovskites for PV, electronic, and optoelectronic applications.

In this paper, we have investigated the nonlinear optical response and theoretical efficiency of CH3NH3PbI3−xClx thin films from the optical transmission and reflection measurements. The dispersion of the complex refractive index is evaluated using the Wemple–DiDomenico single oscillator model. The oscillator energy (E0) of CH3NH3PbI3−xClx follows by an empirical relationship with optical bandgap (Eg) as E0 ≈ 2.41 Eg for chemical dip coating, spray, and E0 ≈ 1.63 Eg for dipping deposited samples, respectively. The long wavelength refractive index, average oscillator wavelength, and oscillator strength are also determined using the Sellmeier oscillator equation. The estimated third-order nonlinear optical susceptibility is found to be the order of 10−12 esu. The incident photon and charge carrier interaction in CH3NH3PbI3−xClx is studied from the dielectric response of the samples. The charge carrier excitation is found higher at lower wavelength and experienced bulk excitation in volume while surface excitation on the surface region. The optical conductivity of CH3NH3PbI3−xClx is notably high, which leads to an increase in carrier transfer through the extrinsic halide perovskite material expedient for higher conversion efficiency. The highest theoretical efficiency of CH3NH3PbI3−xClx is estimated to be 17.4%, which is in excellent agreement with the experimental report. From photosensitivity study, it is confirmed that CH3NH3PbI3−xClx films are highly photosensitive. All these results comprehend that CH3NH3PbI3−xClx is a potential candidate for photonic applications.

In 2021 May, the Dark Energy Spectroscopic Instrument (DESI) began a 5 yr survey of approximately 50 million total extragalactic and Galactic targets. The primary DESI dark-time targets are emission line galaxies, luminous red galaxies, and quasars. In bright time, DESI will focus on two surveys known as the Bright Galaxy Survey and the Milky Way Survey. DESI also observes a selection of “secondary” targets for bespoke science goals. This paper gives an overview of the publicly available pipeline ( desitarget ) used to process targets for DESI observations. Highlights include details of the different DESI survey targeting phases, the targeting ID ( TARGETID ) used to define unique targets, the bitmasks used to indicate a particular type of target, the data model and structure of DESI targeting files, and examples of how to access and use the desitarget code base. This paper will also describe “supporting” DESI target classes, such as standard stars, sky locations, and random catalogs that mimic the angular selection function of DESI targets. The DESI target-selection pipeline is complex and sizable; this paper attempts to summarize the most salient information required to understand and work with DESI targeting data.