Improved device efficiency and lifetime of perovskite light-emitting diodes by size-controlled polyvinylpyrrolidone-capped gold nanoparticles with dipole formation

Abstract

Herein, an unprecedented report is presented on the incorporation of size-dependent gold nanoparticles (AuNPs) with polyvinylpyrrolidone (PVP) capping into a conventional hole transport layer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The hole transport layer blocks ion-diffusion/migration in methylammonium-lead-bromide (MAPbBr3)-based perovskite light-emitting diodes (PeLEDs) as a modified interlayer. The PVP-capped 90 nm AuNP device exhibited a seven-fold increase in efficiency (1.5%) as compared to the device without AuNPs (0.22%), where the device lifetime was also improved by 17-fold. This advancement is ascribed to the far-field scattering of AuNPs, modified work function and carrier trapping/detrapping. The improvement in device lifetime is attributed to PVP-capping of AuNPs which prevents indium diffusion into the perovskite layer and surface ion migration into PEDOT:PSS through the formation of induced electric dipole. The results also indicate that using large AuNPs (> 90 nm) reduces exciton recombination because of the trapping of excess charge carriers due to the large surface area.

The Trade-off Between Efficiency and Stability in Mn2+ Doped Perovskite Light-Emitting Diodes

“…Here, τ1 is a fast decay related to trap-assisted nonradiative recombination at the grain boundaries within the perovskite while τ2 is a slow decay related to radiative recombination inside the grains of the perovskite. 18,54 Table 2 summarizes the τ1, τ2, and τavg for the four devices depicted in Figure 5 at a fluence of approximately 60 pJ/cm 2 . In general, the τavg of higher TFPPO-treated PeLEDs decreases more significantly with device operation.…”

A comparison of molecular iodine evolution on the chemistry of lead and tin perovskites

“…Crucially, MPP tracking at elevated temperatures and illumination, yielded improved device stability when prepared with b-CD, retaining an impressive 88.2% PCE after 1000 h. Similarly, polyvinylpyrrolidone (PVP), a polymeric iodophor widely used as an antiseptic, has also gained recent attention through its ability to form a complex with and act as a reservoir for I 2 capture within perovskites. [196][197][198][199][200][201] Interestingly, conflicting reports have so far been provided as to the exact optimum application with Kang et al choosing to add the iodine-bound form (PVP-I) whereas Yang et al opted for poly(2-vinylpyridine) (P2VP) with no starting bound-iodine. 196,198 In the former approach, the PVP-I provided a reservoir to replace iodine, preventing irreversible loss and depletion.…”