Influence of the electron buffer layer on the photovoltaic performance of planar Sb₂(S_xSe_1‐x)₃ solar cells

Abstract

Appropriate selection of electron buffer layer and understanding its impact on the photo‐generated charge transfer dynamics at the interfaces are critical to enhance the efficiency of solar cells. By optimizing a multilayer electron buffer composed of CdS thin film deposited on TiO2 compact layer, we obtained a power conversion efficiency (PCE) of 5.47% for a planar solar cell of Sb2(SxSe1‐x)3 absorber. The PCE was significantly enhanced in the photovoltaic parameters of planar solar cells fabricated with single‐layer configuration: for example, PCE of 3.99% and 0.79% were obtained when either CdS or TiO2, respectively, were used. Surface photovoltage spectroscopy, transient photovoltage, and electrochemical impedance spectroscopy analyses indicated that the PCE improvement can be ascribed to a combination of 2 factors: (i) better separation and transfer of the photo‐excited free charge, provided by the beneficial energy level alignment between TiO2 and CdS layers, and (ii) sulfur passivation upon incorporation of CdS in a multilayer configuration causing a reduction in the trap states at the interface with Sb2(SxSe1‐x)3.

Sb2(Se1‐xSx)3 Thin‐Film Solar Cells Fabricated by Single‐Source Vapor Transport Deposition

“…It is consistent with the bandgap calculated from the transmittance spectrum of LD‐SbSeS film prepared on blank glass ( Figure S6d, Supporting Information). The bandgap of Sb 2 (Se 1−x S x ) 3 film is a function of S concentration which is expressed by the following equation: …”

“…Various methods have been developed to fabricate the Sb 2 (Se 1‐x S x ) 3 absorber layer. Co‐evaporating Sb 2 Se 3 and S or Sb 2 S 3 is one of the ways to fabricate Sb 2 (Se 1‐x S x ) 3 films and the highest reported efficiency was 6.2% based on the superstrate device structure: fluorine‐doped tin oxide (FTO)/CdS/Sb 2 (Se 1−x S x ) 3 /C‐Ag . Also, by post‐selenizing Sb 2 S 3 films fabricated by solution process, device with the structure of FTO/TiO 2 /Sb 2 (Se 1−x S x ) 3 /spiro‐OMeTAD demonstrated a certified PCE of 5.71% with a selenium‐graded Sb 2 (Se 1−x S x ) 3 absorber layer .…”

Review of Recent Progress in Antimony Chalcogenide‐Based Solar Cells: Materials and Devices

“…Interfacial improvements such as energy band tailoring at interfaces in planar Sb 2 (S x Se 1−x ) 3 solar cells have shown important effects. TiO 2 /CdS hybrid double ETLs for planar Sb 2 (S x Se 1−x ) 3 solar cells have been proved to achieve a higher efficiency of 5.47% compared with single TiO 2 ETL and CdS ETL due to a better separation and transfer of photon‐excited charges and interface sulfur passivation upon incorporation of CdS . Recently, these novel TiO 2 /CdS double ETLs generated an even higher PCE of 5.73% by using hydrothermal processed Sb 2 (S,Se) 3 as absorber, demonstrating a promising double ETL for reducing the bandgap offset and improving the open‐circuit voltage of planar Sb 2 (S x Se 1−x ) 3 solar cells …”

Efficient Double Buffer Layer Sb2 (SexS1–x)3 Thin Film Solar Cell Via Single Source Evaporation

“…Tang et al reported 5.79% PCE using in‐situ‐sulfurization of Sb 2 Se 3 . Oscar et al adopted thermal evaporation of CBD based Sb 2 S 3 and Sb 2 Se 3 mixture to fabricate planar Sb 2 (S 0.47 Se 0.53 ) 3 solar cells with a PCE of 5.47% . Recently, our group utilized co‐evaporation of Sb 2 S 3 and Sb 2 Se 3 double source to implement antimony chalcogenide sample library .…”

“…Oscar et al adopted thermal evaporation of CBD based Sb 2 S 3 and Sb 2 Se 3 mixture to fabricate planar Sb 2 (S 0.47 Se 0.53 ) 3 solar cells with a PCE of 5.47%. [19] Recently, our group utilized co-evaporation of Sb 2 S 3 and Sb 2 Se 3 double source to implement antimony chalcogenide sample library. [9] In the above-mentioned work, two-steps or two sources are utilized to achieve alloy film.…”