Energy level tuned indium arsenide colloidal quantum dot films for efficient photovoltaics

Abstract

We introduce indium arsenide colloidal quantum dot films for photovoltaic devices, fabricated by two-step surface modification. Native ligands and unwanted oxides on the surface are peeled off followed by passivating with incoming atomic or short ligands. The near-infrared-absorbing n-type indium arsenide colloidal quantum dot films can be tuned in energy-level positions up to 0.4 eV depending on the surface chemistry, and consequently, they boost collection efficiency when used in various emerging solar cells. As an example, we demonstrate p–n junction between n-type indium arsenide and p-type lead sulfide colloidal quantum dot layers, which leads to a favorable electronic band alignment and charge extraction from both colloidal quantum dot layers. A certified power conversion efficiency of 7.92% is achieved without additionally supporting carrier transport layers. This study provides richer materials to explore for high-efficiency emerging photovoltaics and will broaden research interest for various optoelectronic applications using the n-type covalent nanocrystal arrays.

III–V colloidal nanocrystals: control of covalent surfaces

“…In parallel with the core/shell heterostructuring, alternative chemical means that remove surface dangling bonds or oxidation layers have been explored (summarized in Table 2). 8,41,75,76 The rst attempt was performed by Olga I. Micic et al, 77 who observed strong band-edge emissions from InP QDs when exposed to dilute solutions of HF or NH 4 F. The uoride chemicals eliminate (passivate) the surface deep states of InP QDs, reected as the suppression of parasitic emission at lower energies with a long recombination lifetime (>500 ns). Later, D. V. Talapin et al unveiled the surface etching of InP QDs with HF caused by the migration of photoexcited charge carriers to the P dangling bonds (Fig.…”

“…4b and c). 8 Additionally, surface ligands can treat the traps for passivation aer the synthesis. However, surface passivation using surface ligands aer the synthesis is considered less effective in III-V nanocrystals when compared with II-VI or IV-VI nanocrystals because of the covalency in surface dangling bonds.…”

“…Colloidal quantum dots (QDs), whose photophysical properties vary depending upon their dimension, are considered to be the most promising candidates for a variety of applications including displays, 1,2 photovoltaics, [3][4][5][6][7][8][9] and biomarkers. [10][11][12] Since 10-70% of the total number of atoms reside at the exterior of nanometer sized QDs, the impact of the QD surface on its photophysical and electrical properties is substantial.…”

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

“…Colloidal quantum dots (QDs) have received remarkable research attention due to their excellent properties such as tuneable bandgaps, multiple exciton effects and excellent stability [1][2][3][4][5][6][7][8] . These unique features facilitate their wide applications in optoelectronic devices such as photodetectors, [9][10][11][12] light emitting diodes [13][14] and photovoltaics [15][16][17] .…”

Design Strategy of Quantum Dot Thin‐Film Solar Cells

“…DOI: 10.1002/smll.202002460 enable the derivation of new materials with a tailored bandgap for nontoxic solar cell. [6,7] Meanwhile, QDs are the most potent materials that can overcome the Shockley-Queisser (S-Q) limit, the p-n junction limit of conventional solar cells, with a single material. The thermal energy loss of photons in a solar cell is reduced by energy conversion management methods such as carrier multiplication, up-and down-conversions, and hot carriers.…”