Thiol and Halometallate, Mutually Passivated Quantum Dot Ink for Photovoltaic Application

Abstract

Tunable-band-gap colloidal QDs are a potential building block to harvest the wide-energy solar spectrum. The solution-phase surface passivation with lead halide-based halometallate ligands has remarkably simplified the processing of quantum dots (QDs) and enabled the proficient use of materials for the development of solar cells. It is, however, shown that the hallometalate ligand passivated QD ink allows the formation of thick crystalline shell layer, which limits the carrier transport of the QD solids. Organic thiols have long been used to develop QD solar cells using the solid-state ligand exchange approach. However, their use is limited in solution-phase passivation due to poor dispersity of thiol-treated QDs in common solvents. In this report, a joint passivation strategy using thiol and halometallate ligand is developed to prepare the QD ink. The mutually passivated QDs show a 50% reduction in shell thickness, reduced trap density, and improved monodispersity in their solid films. These improvements lead to a 4 times increase in carrier mobility and doubling of the diffusion length, which enable the carrier extraction from a much thicker absorbing layer. The photovoltaic devices show a high efficiency of 10.3% and reduced hysteresis effect. The improvement in surface passivation leads to reduced oxygen doping and improved ambient stability of the solar cells.

Hydroiodic Acid Additive Enhanced the Performance and Stability of PbS-QDs Solar Cells via Suppressing Hydroxyl Ligand

“…And the activation energy value of w/HI device is slightly higher than that of the w/o HI devices, which is ascribed to the better passivation in the interface of ZnO and QDs. To investigate the recombination mechanisms of above two kinds of devices, the light-intensity dependences of J sc and V oc were measured to get the device ideality factor n [ 9 , 32 ]. As shown in Fig.…”

“…Solution-processed PbS colloidal quantum dots (CQDs) are among the emerging materials for third-generation photovoltaics in view of their simple process [1], large scale [2], lowcost manufacturing [3], and size-dependent bandgaps [4,5]. In the past decade, surface passivation [6][7][8] and device architecture [9][10][11][12][13][14] have been implemented to improve the photovoltaic performances; the efficiencies of PbS QD solar cells have been realized continuous breakthroughs. Recently, QDs-ink process as a new effective technique applied in PbS-QDs solar cells to refresh a new record of power conversion efficiency (PCE) of 12.6% [15].…”

Perovskite Quantum Dot Solar Cells: An Overview of the Current Advances and Future Perspectives

“…Despite these great advances, the passivating strategies for PQDs are still not thoroughly conclusive. [18,63] Different from other types of colloidal QDs for solar cells (typically chalcogenides or some compounds from group 15) in which prominent advances for passivation were already obtained, [114][115][116][117][118][119] the use of PQDs is quite recent. Using chalcogenide QDs for solar cells has gained ground since 2010, [63,120] whereas the first important results concerning PQDs for this application came out in 2016.…”

Efficient PbS Quantum Dot Solar Cells with Both Mg-Doped ZnO Window Layer and ZnO Nanocrystal Interface Passivation Layer

“…PbS colloidal quantum dot (CQD) solar cells have been rapidly developed in recent years with a certified power conversion efficiency (PCE) up to 13% in an optimal device configuration [1,2]. Compared to traditional photovoltaic technology, PbS CQD solar cells show great potential applications in energy products in view of their low cost, low temperature, and simple solution processing techniques [3][4][5][6][7][8][9][10]. More importantly, the bandgap of PbS CQDs can be easily controlled by varying the size of the CQDs, which enables efficient harvesting of a broad light spectrum from the visible to infrared region.…”