Ag(I)-Thiolate-Protected Silver Nanoclusters for Solar Cells: Electrochemical and Spectroscopic Look into the Photoelectrode/Electrolyte Interface

Abstract

Intrinsic low stability and short excited lifetimes associated with Ag nanoclusters (NCs) are major hurdles that have prevented the full utilization of the many advantages of Ag NCs over their longtime contender, Au NCs, in light energy conversion systems. In this report, we diagnosed the problems of conventional thiolated Ag NCs used for solar cell applications and developed a new synthesis route to form aggregation-induced emission (AIE)type Ag NCs that can significantly overcome these limitations. A series of Ag(0)/Ag(I)-thiolate core/shell-structured NCs with different core sizes were explored for photoelectrodes, and the nature of the two important interfacial events occurring in Ag NCsensitized solar cells (photoinduced electron transfer and charge recombination) were unveiled by in-depth spectroscopic and electrochemical analyses. This work reveals that the subtle interplay between the light absorbing capability, charge separation dynamics, and charge recombination kinetics in the photoelectrode dictates the solar cell performance. In addition, we demonstrate significant improvement in the photocurrent stability and light conversion efficiency that have not been achieved previously. Our comprehensive understanding of the critical parameters that limit the light conversion efficiency lays a foundation on which new principles for designing Ag NCs for efficient light energy conversion can be built.

Tuning atomically precise metal nanocluster mediated photoelectrocatalysis via a non-conjugated polymer

“…Atomically precise metal nanoclusters (NCs, <2 nm) consisting of a definite number of ligands and metal atoms are an emerging subgenre of metal nanomaterials. 1–3 Metal NCs feature molecule-like discrete energy band structures, peculiar atom-packing arrangements, quantum size effect and abundant active sites, 4,5 which endow them with quasi-semiconductor properties such as a highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) transition gap, quantized charging, and strong luminescence, 6–8 thereby diversifying the physicochemical properties of metal NCs for multifarious applications ( e.g. , energy storage and catalysis).…”

Modulation of the photoelectrochemical behavior of Au nanocluster–TiO2 electrode by doping

“…Recombination resistance (R r ) is directly related to V OC in the solar cells. 5,6 As given in Fig. 6A, NC-2-SC, which exhibited the highest V OC , had the highest R r , and the R r values of all MCSSCs followed the same trend as did V OC (NC-2-SC > NC-1-SC > NC-3-SC > NC-4-SC).…”

“…The absence of Landau damping from 4d electrons due to positions relative to 5s electrons produces a stronger quantum confinement effect and induces optical properties that are superior to those of Au NCs. 5 , 55 Therefore, doping of Au NCs with Ag can increase the extinction coefficients of bimetallic NCs, making them more efficient light harvesters than pure Au NCs. Indeed, the extinction coefficients of Ag-doped Au 18 (SR) 14 were significantly higher than those of their pure counterparts ( Fig.…”

“…2,3 The feasibility of using thiolated NCs as a photosensitizer in solar cell applications has been demonstrated, and a newly-coined term-metal-nanocluster-sensitized solar cells (MCSSCs)-has been well-described. [4][5][6][7] Early breakthroughs by the Kamat group and others, including recent reports by our group, are setting the stage for the development of efficient MCSSCs by revealing the effects of various performance-dictating factors. [7][8][9][10][11][12] For instance, the absorption capability of an NC is usually a function of its size.…”

Self‐Assembly of Precision Noble Metal Nanoclusters: Hierarchical Structural Complexity, Colloidal Superstructures, and Applications

“…[ 13,22–24 ] NCs prepared from gold and silver metals have received substantial attention in recent past due to their size‐dependent electronic, [ 3,9,17 ] optical absorption, [ 6,9 ] photoluminescence (PL), [ 25–32 ] and magnetic properties. [ 33,34 ] The specific geometry and intrinsic photophysical properties of NCs have been efficiently used to probe catalytic reactions, [ 35–50 ] toxic metal ions/molecules, [ 51–55 ] biological events, [ 56–68 ] solar energy conversion, [ 69–73 ] and light‐emitting device fabrication. [ 74,75 ] A large number of NCs stapled with thiols, [ 6,7 ] phosphenes, [ 76–84 ] and selenols [ 85–89 ] have been synthesized in liquid, [ 6,7 ] solid, [ 90 ] and interface layers.…”