Charge Photogeneration and Transport in AgBiS₂ Nanocrystal Films for Photovoltaics

Abstract

Solution‐processed AgBiS2 nanocrystal films are a promising material for nontoxic, earth‐abundant solar cells. While solar cells with good device efficiency are demonstrated, so far, hardly anything is known about charge generation, transport, and recombination processes in these films. Here, a photoinduced time‐resolved microwave conductivity study on AgBiS2 nanocrystal films is presented. By modeling the experimental data with density‐dependent recombination processes, the product of the temperature‐dependent electron and hole quantum yield and mobility, and the electron and hole recombination kinetics are determined.

Eco-Friendly AgBiS2 Nanocrystal/ZnO Nanowire Heterojunction Solar Cells with Enhanced Carrier Collection Efficiency

“…In contrast, in the case of NW-200/120, most of the incident photons were absorbed in the interdigitated layer, photogenerated electrons were efficiently collected by ZnO NWs, and photogenerated holes left behind in the AgBiS 2 region moved to the Au back contact through the 120 nm-thick AgBiS 2 capping layer. However, as reported in the previous paper, the diffusion length of holes in AgBiS 2 layers (approximately 150 nm) is longer than that of the electrons (60 nm) and even longer than the capping layer thickness. Therefore, even though NW-200/120 had the additional AgBiS 2 layer (capping layer) as thick as the AgBiS 2 active layer of NP-120, NW-200/120 outperformed NP-120.…”

“…Combined with the energy level determined by ultraviolet photoelectron spectroscopy (UPS), AgBiS 2 NC films were found to be a p -type semiconductor (Figure S3). The hole and electron diffusion lengths of AgBiS 2 NCs are reported to be around 150 and 60 nm, respectively . The much shorter diffusion length of electrons, which act as minority carriers in AgBiS 2 NCs, indicates that application of the ZnO NWs is important for efficient electron collection in AgBiS 2 solar cells.…”

Alternative Lone‐Pair ns2‐Cation‐Based Semiconductors beyond Lead Halide Perovskites for Optoelectronic Applications

“…[ 168,169 ] It has been reported that the mobilities of electrons and holes in AgBiS 2 NC films are on the order of 10 −1 cm 2 V −1 s −1 at room temperature. [ 170 ] Recently, Ceballos et al. modified synthetic approach to minimize the colloidal AgBiS 2 NC surface to volume ratio, leading to enhanced carrier mobility and reduced recombination.…”

Design Strategy of Quantum Dot Thin‐Film Solar Cells

“…[ 107,108 ] In addition, carrier diffusion length of iodide‐treated AgBiS 2 nanocrystal film is up to 60 nm due to the uncontrolled defect traps, limiting the thickness of active layer in solar cells. [ 109 ]…”