High Performance Organic Solar Cells Processed with Non-halogen Solvents and Additives

prohibitionMasterdCollectio

Multi-donor random terpolymers based on benzodithiophene and dithienosilole segments with different monomer compositions for high-performance polymer solar cells

We synthesized and characterized a series of new random terpolymers which are composed of two electron-rich segments, thienyl-substituted benzo[1,2-b:4,5-b’]dithiophene (BDT) and dithieno[3,2-b:2’,3’-d]silole (DTS), and one electron- deficient segment, thieno[3,4-c]pyrrole-4,6-dione (TPD), with different ratio of DTS segment to BDT segment (25%, 50%, and 75% DTS). The compositional effect of the random terpolymers on physicochemical properties and photovoltaic performances were studied. The different compositions of BDT and DTS segments in the conjugated backbone of the terpolymers had a crucial effect on the electrochemical properties of the random terpolymers. PTPD-BDT75-DTS25 (P1) with monomeric composition of BDT and DTS (75:25) segments showed excellent light harvesting ability, high charge carrier mobility, and low-lying HOMO energy level. Moreover, the photovoltaic performance of the random terpolymer based BHJ PSCs was strongly influenced by the composition of BDT and DTS segments in the conjugated backbones of the terpolymers. The inverted BHJ PSCs based on the PTPD-BDT75- DTS25 exhibited a Voc of 0.94 V, a Jsc of 10.83 mA/cm2, and a FF of 56.52%, leading to a high PCE of 5.78%.[Figure not available: see fulltext.] © 2017 The Polymer Society of Korea and Springer Science+Business Media B.V., part of Springer Nature1

Stable pure-iodide wide-band-gap perovskites for efficient Si tandem cells via kinetically controlled phase evolution

Halide perovskites, promising top-cell materials for efficient Si tan-dem solar cells, suffer from halide segregation, which results from the halide mixing necessary for achieving band-gap widening. We report pure-iodide wide-band-gap perovskite top cells that are fundamentally free of halide segregation. Cs and dimethylammo-nium cations were incorporated simultaneously into the A-site of perovskite structure to increase the band gap while maintaining the tolerance factor. However, the incorporation of dual cations re-sulted in the simultaneous formation of orthorhombic and hexago-nal secondary phases rather than forming the pure perovskite phase, owing to the different precipitation kinetics between cat-ions. We demonstrated that this strategy can only be implemented by the phase-controlled nucleation of the Cs-rich composition that governs the desired phase evolution. The pure-iodide perovskite top cell exhibited excellent photo-stability (1% degradation after 1,000 h of continuous operation; ISOS-L-1I, white LED), and its Si tandem exhibited a high conversion efficiency of 29.4% (28.37% certified).11Nsciescopu