Metal-halide perovskites offer great potential to realize low-cost and flexible next-generation solar cells. Low-temperature processed organic hole-transporting layers play an important role in advancing device efficiencies and stabilities. Inexpensive and stable hole-transporting materials are highly desirable towards the scaling up of perovskite solar cells. Here, we report a new group of aniline-based enamine hole-transporting materials obtained via a one-step synthesis procedure, This article is protected by copyright. All rights reserved. without using a transition metal catalyst, from very common and inexpensive aniline precursors. This results in a material cost reduction to less than 1/5 of that for the archetypal spiro-OMeTAD. Perovskite solar cells using an enamine V1091 hole transporting material exhibit a champion power conversion efficiency of over 20%. Importantly, the unsealed devices with V1091 retain 96% of their original efficiency after storage in ambient air, with a relative humidity of 45% for over 800 hours, while the devices fabricated using spiro-OMeTAD dropped down to 42% of their original efficiency after aging. Additionally, these materials can be processed via both solution and vacuum processes, which we believe will open up new possibilities for interlayers used in large-area all perovskite tandem cells, as well as many other optoelectronic device applications.
The power conversion efficiency of perovskite solar cells is approaching the Shockley-Queisser limit, therefore this technology is next to the commercialization stage. The inexpensive and stable hole transporting materials are...
Star-shaped charge-transporting materials with a triphenylamine (TPA) core and various phenylethenyl side arm(s) were obtained in a one-step synthetic procedure from commercially available and relatively inexpensive starting materials. Crystallinity, glass-transition temperature, size of the π-conjugated system, energy levels, and the way molecules pack in the solid state can be significantly influenced by variation of the structure of these side arm(s). An increase in the number of phenylethenyl side arms was found to hinder intramolecular motions of the TPA core, and thereby provide significant enhancement of the fluorescence quantum yield of the TPA derivatives in solution. On the other hand, a larger number of side arms facilitated exciton migration through the dense side-arm network formed in the solid state and, thus, considerably reduces fluorescence efficiency by migration-assisted nonradiative relaxation. This dense network enables charges to move more rapidly through the hole-transport material layer, which results in very good charge drift mobility (μ up to 0.017 cm(2) V (-1) s(-1)).
In a short period of time rapid development of perovskite solar cells attracted a lot of attention in the science community with record for power conversion efficiency being broken every...
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