High Open‐Circuit Voltage in Full‐Inorganic Sb₂S₃ Solar Cell via Modified Zn‐Doped TiO₂ Electron Transport Layer

Abstract

Antimony sulfide (Sb2S3) is emerging as a popular photovoltaic candidate for thin‐film solar cells due to its large absorption coefficient, suitable bandgap, nontoxic, and earth‐abundant nature. The performance of thermally evaporated Sb2S3 devices is severely restricted by interfacial recombination leading to high open‐circuit voltage (VOC) losses. CdS as electron transport layer (ETL) has overcome this problem, but triggered lower JSC issues due to parasitic absorption loss conceding to its smaller bandgap. Herein, a spray pyrolysis method is adopted for the deposition of a uniform and compact Zn‐doped TiO2 film with tuned energy levels to facilitate charge extraction and transport. The solar cell fabricated with a modified TiO2 ETL holds superior interface quality, high build‐in potential, and suppressed recombination losses, therefore pronouncedly improves the VOC. As a result, the efficiency of the device is boosted from 4.41% to 5.16%, a record VOC of 702 mV for Cd‐free full‐inorganic Sb2S3 solar cell is achieved. These findings are expected to be implemented in other Sb‐chalcogenide solar cells to further enhance the device performance.

Boosting VOC of antimony chalcogenide solar cells: A review on interfaces and defects

“…have been used to address these disadvantages. [80,82] For example, Niobium (Nb) is doped into TiO 2 to modify the photo-electrical properties of TiO 2 film. [80] Composition engineering…”

“…[81] More recently, Ishaq et al used Zn doped TiO 2 as ETL in planar-type Sb 2 S 3 solar cells. [82] They found that Zn-doped TiO 2 enhanced the interface quality and induced a upward shift of the Fermi level from 4.25 to 4.19 eV, which leads to the improvement of charge extraction and transportation as well as the suppression of charge recombination losses.…”

Wide Bandgap Sb2S3 Solar Cells

“…Finally, the device based on TiO 2 ETL modified via ZnCl 2 delivered the optimal PCE of 7.08%. While, apart from Sb 2 S 3 surface modifications by an inorganic salt zinc halide, Ishaq et al [114] in a collaboration with our group, introduced a Zn doping strategy in the TiO 2 ETL, by adding different concentrations of ZnCl 2 powder to the TiO 2 solution. In the end, the PCE of the device based on pure-TiO 2 was 4.41%, and due to the excellent junction quality with Zn-TiO 2 , the PCE of the device reached 5.16%, with a V OC of 702 mV for Cd-free full-inorganic Sb 2 S 3 solar cell.…”

“…Reproduced with permission. [114] Copyright 2020, Wiley-VCH. d) Schematic diagram of selenization of Sb 2 S 3 photovoltaic device in two-zone tube furnace.…”

Functional ZnO/TiO2 Bilayer as Electron Transport Material for Solution‐Processed Sb2S3 Solar Cells

“…Recently, Ishaq et al [ 39 ] reported a Sb 2 S 3 planar solar cell using Zn‐doped TiO 2 compact layers obtained by spray pyrolysis and Sb 2 S 3 films obtained by a rapid thermal evaporation process. They found that by controlling the Zn concentration in the spray pyrolysis solution, the morphology, crystallinity, and energy bands of TiO 2 can be effectively tuned.…”