Surface Ligand Management Aided by a Secondary Amine Enables Increased Synthesis Yield of CsPbI₃ Perovskite Quantum Dots and High Photovoltaic Performance

Abstract

Lead halide perovskite quantum dots (PQDs) or more broadly, nanocrystals possess advantageous features for solution-processed photovoltaic devices. The nanocrystal surface ligands play a crucial role in the transport of photogenerated carriers and ultimately affect the overall performance of PQD solar cells. We have demonstrated significantly improved CsPbI 3 PQD synthetic yield and solar cells performance through surface ligand management. The treatment of a secondary amine, di-n-propylamine (DPA), provides a mild and efficient approach to control the surfaces ligand density of PQDs, which has apparently different working mechanism compared to the previously reported surface treatment. Using an optimal DPA concentration, the treatment can simultaneously remove both long chain insulating surface ligands of oleic acid and oleylamine, even for unpurified This article is protected by copyright. All rights reserved.PQDs with high ligand density. As a result, the electrical coupling between PQDs is enhanced; leading to improved charge transport, reduced carrier recombination, and a high power conversion efficiency (PCE) approaching 15% for CsPbI 3 PQD based solar cells. In addition, the production yield of CsPbI 3 PQDs can be increased by a factor of 8. These results highlight the importance of developing new ligand-management strategies, specifically for emerging PQDs to achieve scalable and high-performance perovskite-based optoelectronic devices.All-inorganic perovskite quantum dots (PQDs) exhibit high photoluminescence quantum yields (PLQY), spectrally tunable bandgap, flexible compositional control, and crystalline strain benefits. [1][2][3][4] PQDs are relatively easy to synthesize which opens a route for next generation optoelectronic devices, as well as opportunities for exploring fundamental properties at nanoscale. [5,6] For photovoltaics (PVs), colloidal CsPbI 3 PQD solar cells were first demonstrated with a power

In Situ Ligand Bonding Management of CsPbI3 Perovskite Quantum Dots Enables High‐Performance Photovoltaics and Red Light‐Emitting Diodes

“…Finally,t odemonstrate the merit of L-PHE passivated CsPbI 3 QDs for application in optoelectronic devices,w ef abricated QD solar cells and red LEDs using CsPbI 3 QDs w/wo L-PHE passivation as light absorbing and luminescent layer, Figure 5a,t he solar cell device architecture consists of al ayered structure of FTO/TiO 2 / CsPbI 3 QDs/PTAA/MoO 3 /Ag, [31] in which TiO 2 and PTAA are the electron-transport and hole-transport layer, respectively.A ss hown in Figure 5b,t he pristine CsPbI 3 QD solar cells without any additional treatment show ab est efficiency of 13.59 %, similar to previous reports. [27][28][29][30][31][32][33][34] Forthe in situ L-PHE treated QDs,a fter optimization, an enhanced shortcircuit current density (J sc )of15.23 mA cm À2 ,asimilar opencircuit voltage (V oc )of1.23 Vand afill factor (FF) of 0.78 are achieved, giving an improved PCE of 14.62 %, which is among the highest reported PCE values for CsPbI 3 QDs solar cells (Supporting Information, Table S1). Both devices exhibit similar J-V hysteresis (Supporting Information, Figure S8).…”

Flexible and efficient perovskite quantum dot solar cells via hybrid interfacial architecture

“…QDs exhibit high photoluminescence (PL) quantum yields due to impressive defect tolerance 19 – 22 , which translates into high open-circuit voltages. Advances in CsPbI 3 QD solar cells have enabled high efficiency over 15% to be achieved, showing great potential for photovoltaics 23 , 24 . Importantly, fabrication of perovskite QDs involves colloidal synthesis and processing using a variety of more common nonpolar organic solvents such as hexane, octane, or toluene at room temperature, whereas thin-film perovskites are normally processed from polar aprotic solvents such as N , N -dimethylformamide, which is quite toxic, opening a new platform for developing high-performance QD optoelectronic devices 25 – 29 .…”

Mixed lead source precursors for producing light absorption layers of perovskite solar cells

“…In recent years, perovskite solar cells (PSCs) have become a research focus for their excellent photovoltaic performance and simple fabrication procedure. [1][2][3][4][5][6][7][8][9][10][11] These merits are mainly attributed to the light absorption materials of organic lead halides, which have a perovskite crystal structure of ABX 3 . Previous investigations indicate that the composition of precursor solutions is an important factor to determine the quality of perovskite layers.…”