In Situ Passivation for Efficient PbS Quantum Dot Solar Cells by Precursor Engineering

Abstract

Current efforts on lead sulfide quantum dot (PbS QD) solar cells are mostly paid to the device architecture engineering and postsynthetic surface modification, while very rare work regarding the optimization of PbS synthesis is reported. Here, PbS QDs are successfully synthesized using PbO and PbAc · 3H O as the lead sources. QD solar cells based on PbAc-PbS have demonstrated a high power conversion efficiency (PCE) of 10.82% (and independently certificated values of 10.62%), which is significantly higher than the PCE of 9.39% for PbO-PbS QD based ones. For the first time, systematic investigations are carried out on the effect of lead precursor engineering on the device performance. It is revealed that acetate can act as an efficient capping ligands together with oleic acid, providing better surface coverage and replace some of the harmful hydroxyl (OH) ligands during the synthesis. Then the acetate on the surface can be exchanged by iodide and lead to desired passivation. This work demonstrates that the precursor engineering has great potential in performance improvement. It is also pointed out that the initial synthesis is an often neglected but critical stage and has abundant room for optimization to further improve the quality of the resultant QDs, leading to breakthrough efficiency.

14.1% CsPbI3 Perovskite Quantum Dot Solar Cells via Cesium Cation Passivation

“…[8] As shown in Figure 4a, both the control and CsAc treated cells exhibit α values of close to 1, indicating almost no bimolecular recombination in CsPbI 3 QD devices. The power-law dependence of J SC upon the light intensity generally follows the relationship of J SC ∝ I α , where I is the light intensity and α is the exponential factor.…”

“…Due to the great efforts on CQDs synthesis modification, [7][8][9] surface passivation, [10][11][12] and device fabrication optimization, [13][14][15][16] PbS QD solar cells continue to progress at an extraordinary rate, improving overall efficiencies by ≈1% per year and currently have a certified power conversion efficiency (PCE) exceeding 12%. Due to the great efforts on CQDs synthesis modification, [7][8][9] surface passivation, [10][11][12] and device fabrication optimization, [13][14][15][16] PbS QD solar cells continue to progress at an extraordinary rate, improving overall efficiencies by ≈1% per year and currently have a certified power conversion efficiency (PCE) exceeding 12%.…”

“…Energy Mater. [8,17,46] It has been shown that lattice point defects such as vacancies, interstitials, and substitutions in mental halide perovskites are detrimental to the performance of solar cell devices. Peak shift after treatment suggests change of chemical bonding which may be a result of surface or environmental composition change within the CsPbI 3 QDs.…”

Highly Stabilized Quantum Dot Ink for Efficient Infrared Light Absorbing Solar Cells

“…[26,28] It is worthy to note that the surface topography largely affects the optical interference in a QDSC, thus affecting the device photovoltaic performance. [22,43,44] To this extent, to verify if the OA ligand was quantitative removed, the Fourier-transform infrared (FTIR) spectrum was used to investigate the QD solid film before and after ligand exchange, as shown in Figure 2e. The method for the ligand exchange of QDs or deposition of a QD solid film may affect the crystal structures of a QD solid film.…”

“…In Figure 2f,g, the characteristic peaks of I 3d and Pb 4f core levels are shown and normalized to maximum intensity and S 2p respectively ( Figure S6a, Supporting Information). [44,45] The Pb 4f peak (Figure 2g) shifts slightly to higher binding energy (BE) for PbS-PbX 2 QDs (138.1 eV) than that of PbS-AI QDs (137.9 eV) and both signals are indicative of a Pb 2+ oxidation state. It suggests an improved purification process and surface chemistry in PbS-AI QDs with reduced vacancies and traps, which is important for exciton generation and charge transport.…”