Conductive Phosphine Oxide Passivator Enables Efficient Perovskite Light-Emitting Diodes

Abstract

Recently, surface passivation has been proved to be an essential approach for obtaining efficient and stable perovskite light-emitting diodes (Pero-LEDs). Phosphine oxides performed well as passivators in many reports. However, the most commonly used phosphine oxides are insulators, which may inhibit carrier transport between the perovskite emitter and charge-transporter layers, limiting the corresponding device performance. Here, 2,7-bis­(diphenylphosphoryl)-9,9′-spirobifluorene (SPPO13), a conductive molecule with two phosphine oxide functional groups, is introduced to modify the perovskite emitting layer. The bifunctional SPPO13 can passivate the nonradiative defects of perovskite and promote electron injection at the interface of perovskite emitter and electron-transporter layers. As a result, the corresponding Pero-LEDs obtain a maximum external quantum efficiency (EQE) of 22.3%. In addition, the Pero-LEDs achieve extremely high brightness with a maximum of around 190 000 cd/m2.

Understanding and minimizing non-radiative recombination losses in perovskite light-emitting diodes

“…13,45 The formation of such interfacial defects is mostly correlated with the poor affinity of each layer at the interfaces, which increases the difficulties in film deposition and thus may lead to film discontinuity with pinholes. 46 Such interfacial defects not only exacerbate non-radiative recombination, 7,45 but also impose an adverse impact on the efficient injection of charge carriers. 47 The losses associated with interface-induced recombination could be mitigated by defect passivation and interfacial engineering.…”

Efficient and Stable Self-Assembly Blue-Emitting CsPbBr3 Nanoplatelets with Self-Repaired Surface Defects

“…Benefiting from the excellent optoelectronic properties, such as a high photoluminescence quantum yield (PLQY), narrow full width at half-maximum (FWHM), high color purity, and tunable band gaps, all-inorganic lead halide perovskites (CsPbX 3 , X = Cl, Br, and I) have been extensively investigated in solid-state lighting and high-definition displays in the past few years. − Due to the high defect tolerance relative to traditional metal chalcogenide semiconductor dots, CsPbX 3 nanocrystals (NCs) show higher PLQY without complex core–shell passivation. , To date, the PLQY of bromide- and iodide-based CsPbX 3 with green and red emission has been reported to achieve unity, respectively. , Besides, the external quantum efficiencies (EQEs) of light-emitting diodes (LEDs) based on these materials have exceeded 20%. − However, comparatively, the blue-emitting CsPbX 3 with high PLQY is still rarely reported. Moreover, the great drop in luminous efficiency during device manufacture makes its EQE lag far behind their counterparts.…”

Ionogel-perovskite matrix enabling highly efficient and stable flexible solar cells towards fully-R2R fabrication

“…While polymers or crosslinked networks are stable at grain boundaries and enable good encapsulation, they usually have a single dimension and simplex passivation site, as well as poor carrier mobility. [19][20][21] Furthermore, functional materials with adhesive, buffering and/or self-healing attributes have also been introduced at grain boundaries or interfaces in order to dissipate energy and resist brittleness. [22][23][24][25][26] However, the breaking elongation of these materials is usually low, and damaged materials cannot be repaired or require extra energy input, such as further thermal annealing, to be repaired.…”