NOVELTY - Substituted pyrrol-1-yl compounds (I) are new.    USE - (I) are useful in: a first device and a formulation (all claimed); as emitters in phosphorescent organic OLEDs; consumer products including flat panel displays, computer monitors, medical monitors, TV, billboards, light for interior or exterior illumination and/or signaling, heads up displays, fully transparent displays, flexible displays, laser printers, telephones, cell phones, personal digital assistants, laptop computers, digital cameras, camcorders, viewfinders, microdisplays, 3-dimensional displays, vehicles, a large area wall, theater or stadium screen, or a sign; and organic solar cells and organic photodetectors.    ADVANTAGE - (I) exhibit a high melting point resulting in a large gap between the sublimation temperature, improved stability during the mass production process of organic LEDs, and improved takt time.    DETAILED DESCRIPTION - Substituted pyrrol-1-yl compounds of formula (I) are new.    Ring A1a and B1a = 5-membered or 6-membered carbocyclyl or heterocyclyl;    X1a = neutral donor comprising N, C or P;    R1a-R1d = H, deuterium, halo, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, and/or phosphino, where R1a and R1b are mono, di, tri or tetra substitution, or no substitution;    R1s = halo, alkyl, cycloalkyl, heteroalkyl, arylalkyl, alkoxy, aryloxy, amino, silyl, alkenyl, cycloalkenyl, heteroalkenyl, alkynyl, aryl, heteroaryl, acyl, carbonyl, carboxylic acid, ester, nitrile, isonitrile, sulfanyl, sulfinyl, sulfonyl, and/or phosphino; or    any two adjacent substituents are optionally joined = ring, which can be further substituted;    L1a = coordinated to a metal M1a;    M1a = coordinated to other ligands; and    L1a optionally linked with other ligands = tridentate, tetradentate, pentadentate or hexadentate ligand.    INDEPENDENT CLAIMS are also included for:    (1) a first device comprising a first organic light emitting device, where the first organic light emitting device comprises an anode, a cathode, and an organic layer, disposed between the anode and the cathode, comprising a compound that comprises the first ligand L1a (I); and    (2) a formulation comprising a compound that comprises the first ligand L1a (I).