Direct Hydrothermal Deposition of Antimony Triselenide Films for Efficient Planar Heterojunction Solar Cells

Abstract

Antimony selenide (Sb 2 Se 3 ) has attracted increasing attention in photovoltaic applications due to its unique quasi-one-dimensional crystal structure, suitable optical band gap with a high extinction coefficient, and excellent stability. As a promising light-harvesting material, the available synthetic methods for the fabrication of a high-quality film have been quite limited and seriously impeded both the fundamental study and the efficiency improvement. Here, we developed a facile and low-cost hydrothermal method for in situ deposition of Sb 2 Se 3 films for solar cell applications. In this process, we apply KSbC 4 H 4 O 7 and Na 2 SeSO 3 as the antimony and selenium sources, respectively, in which thiourea (TU) serves as an additive to suppress the formation of Sb 2 O 3 impurities. As a result, improved phase purity and enhanced crystallinity of the Sb 2 Se 3 film are thus obtained, along with decreased trap states. Finally, the planar heterojunction Sb 2 Se 3 solar cell delivered a power conversion efficiency of 7.9%, which is thus far the highest reported efficiency among solution-processed Sb 2 Se 3 solar cells. This simple procedure and efficiency achievement demonstrate the great potential of the hydrothermal deposition process for the fabrication of high-efficiency Sb 2 Se 3 solar cells.

Crystal Growth Promotion and Defects Healing Enable Minimum Open‐Circuit Voltage Deficit in Antimony Selenide Solar Cells

“…Thus, high-quality Sb 2 Se 3 absorber layer should be first prepared with controllable deposition processes and growth dynamics. Various film deposition techniques, such as hydrothermal deposition, [23] solution processing, [24] thermal (or rapid thermal) evaporation, [12,25] close-spaced sublimation (CSS), [26] pulsed-laser deposition (PLD), [27] magnetron sputtering deposition (MSD), [18] and vapor transport deposition (VTD), [9] have been developed to prepare Sb 2 Se 3 absorber layer. Among them, the VTD processed Sb 2 Se 3 thin film showed an improved crystallinity, reduced deep defects, and suppressed trapassisted recombination, leading to a superstrate structured champion Sb 2 Se 3 solar cell (PCE = 7.6%, V OC = 0.42 V), as reported by Tang et al [9] In parallel, our group recently displayed a selfassembled growth of Sb 2 Se 3 thin film with large crystal grains, benign preferential orientation, and accurate chemical composition via an effective MSD and post-selenization involved process, resulting in an interesting substrate structured Sb 2 Se 3 solar cell (PCE = 6.84%, V OC = 0.504 V).…”

“…Thus, high‐quality Sb 2 Se 3 absorber layer should be first prepared with controllable deposition processes and growth dynamics. Various film deposition techniques, such as hydrothermal deposition, [ 23 ] solution processing, [ 24 ] thermal (or rapid thermal) evaporation, [ 12 , 25 ] close‐spaced sublimation (CSS), [ 26 ] pulsed‐laser deposition (PLD), [ 27 ] magnetron sputtering deposition (MSD), [ 18 ] and vapor transport deposition (VTD), [ 9 ] have been developed to prepare Sb 2 Se 3 absorber layer. Among them, the VTD processed Sb 2 Se 3 thin film showed an improved crystallinity, reduced deep defects, and suppressed trap‐assisted recombination, leading to a superstrate structured champion Sb 2 Se 3 solar cell (PCE = 7.6%, V OC = 0.42 V), as reported by Tang et al.…”

Interface Modification Uncovers the Potential Application of SnO2/TiO2 Double Electron Transport Layer in Efficient Cadmium‐Free Sb2Se3 Devices

“…Currently, although the champion efficiency of Sb 2 Se 3 TFSC is 9.2%, a pure CdS or Cd doped thin film is prevalently adopted as the electron transport layer (ETL) or buffer layer for most of the efficient Sb 2 Se 3 TFSC with superstrate or substrate configuration. [9][10][14][15][16][17][18][19] Considering the short circuit current density (J sc ) of Sb 2 Se 3 TFSC will be limited by the parasitic absorption of CdS layer (2.4 eV) in wavelength below 520 nm, and the green environmental demands today, avoiding or reducing the usage of cadmium element remains an important issue for the future development of Sb 2 Se 3 technology. Thus, searching for the proper Cd-free ETL is very important.…”

Nanoepitaxy Growth of Sb2Se3 Nanorod Arrays on Mixed‐Oriented Transparent Conducting Oxide‐Coated Glass for Efficient and Quasiomnidirectional Solar Cells

“…[14] Tang's group reported the fabrication of preferentially [211]-and [221]-oriented Sb 2 Se 3 thin-film solar cells, and the device parameters benefitted from the lower resistance, the benign grain boundaries, and the controlled carrier transport due to the proper ribbon arrangement along the growth direction. [7b] Recently, many methods and techniques such as thermal evaporation, [15] rapid thermal evaporation, [7b,16] sputtering, [17] close spaced sublimation (CSS), [18] vapor transport deposition (VTD), [19] pulsed electron deposition, [20] pulsed laser deposition, [21] and hydrothermal deposition [22] have been developed to control the [211]/[221] orientations of Sb 2 Se 3 absorber. [23] Recently we have demonstrated solar cells based on aligned Sb 2 Se 3 nanorod arrays (NRAs) grown using the CSS technique, in which the (Sb 4 Se 6 ) n ribbons were grown perpendicular to the substrate surface, exhibiting efficient photogenerated carrier extraction for the anisotropic 1D NRA structure along [001] direction.…”

“…[ 14 ] Tang's group reported the fabrication of preferentially [211]‐ and [221]‐oriented Sb 2 Se 3 thin‐film solar cells, and the device parameters benefitted from the lower resistance, the benign grain boundaries, and the controlled carrier transport due to the proper ribbon arrangement along the growth direction [7b] . Recently, many methods and techniques such as thermal evaporation, [ 15 ] rapid thermal evaporation, [7b,16] sputtering, [ 17 ] close spaced sublimation (CSS), [ 18 ] vapor transport deposition (VTD), [ 19 ] pulsed electron deposition, [ 20 ] pulsed laser deposition, [ 21 ] and hydrothermal deposition [ 22 ] have been developed to control the [211]/[221] orientations of Sb 2 Se 3 absorber. [ 23 ]…”