Abstract
Focusing on the critical bottleneck of severe open-circuit voltage loss in Sb2Se3 solar cells, the research team proposed a composition-controlled carrier polarity strategy. By constructing a p-n homojunction structure within the absorber layer, the built-in electric field of the device was significantly enhanced and non-radiative recombination was effectively suppressed, achieving synergistic improvement in device performance.
Research Breakthrough
Recently, Professor Tang Rongfeng from the School of Microelectronics at Hefei University of Technology, in collaboration with Professor Chen Tao from the University of Science and Technology of China, achieved new progress in antimony selenide (Sb2Se3) photoelectric conversion device research. Their findings were published in Nature Photonics under the title "Internal Homojunction Sb2Se3 Solar Cell."
Background: Sb2Se3 as a Promising Material
As an emerging light-absorbing semiconductor material, Sb2Se3 possesses a near-ideal bandgap (1.1-1.3 eV), high absorption coefficient, and excellent thermal and chemical stability, making it a highly promising next-generation light-absorbing layer material. However, the current efficiency of Sb2Se3-based devices still falls significantly below that of mature technologies such as CdTe and Cu(In,Ga)Se2. The core bottleneck lies in severe open-circuit voltage loss, primarily caused by a weak built-in electric field within the device that fails to provide sufficient carrier separation driving force. Meanwhile, a large number of deep-level defects in the bulk and at the interfaces of the absorber layer lead to serious non-radiative recombination losses.
Key Innovations
To address these challenges, the research team proposed a composition-driven intrinsic doping strategy. By controlling the Se and Sb chemical potentials during thermal evaporation, they achieved controllable switching of the conductivity type of Sb2Se3 thin films between n-type and p-type, with carrier concentrations exceeding 1014 cm-3.
Using sequential deposition to construct an n/p-type Sb2Se3 homojunction, they introduced an additional built-in electric field and widened the depletion region, thereby enhancing carrier separation, reducing defect state density, and suppressing non-radiative recombination.
Through combined characterization using theoretical calculations, ultrafast spectroscopy, and depth-resolved simulations, the team confirmed that the homojunction forms a built-in potential gradient that accelerates carrier transport and reduces recombination losses by more than one order of magnitude.
Achieved Performance
The resulting Sb2Se3 optoelectronic device achieved an efficiency of 10.15% with an open-circuit voltage loss of only 0.459 V, reaching an advanced level for this material system. This work provides new insights for reducing voltage losses in Sb2Se3 optoelectronic devices and offers an important reference for performance optimization and device design of antimony-based chalcogenide optoelectronic devices.
