Details

Autor(en) / Beteiligte

• Sheikh, Md. Abdul Kuddus
• Singh, Son
• Abdur, Rahim
• Lee, Sung-Min
• Kim, Jae-Hun
• Nam, Ho-Seok
• Lee, Hyunseung
• Lee, Jaegab

Titel

Effects of the PbBr2:PbI2 Molar Ratio on the Formation of Lead Halide Thin Films, and the Ratio’s Application for High Performance and Wide Bandgap Solar Cells

Ist Teil von

• Materials, 2022-01, Vol.15 (3), p.837

Ort / Verlag

Basel: MDPI AG

Erscheinungsjahr

2022

Link zum Volltext

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• We investigate the effects of the molar ratio (x) of PbBr2 on the phases, microstructure, surface morphology, optical properties, and structural defects of mixed lead halides PbI2(1−x)Br2x for use in solar cell devices. Results indicate that as x increased to 0.3, the surface morphology continued to improve, accompanied by the growth of PbI2 grains. This resulted in lead halide films with a very smooth and continuous morphology, including large grains when the film was formed at x = 0.3. In addition, the microstructure changed from (001)-oriented pure PbI2 to a highly (001)-oriented β (PbI2-rich) phase. The plausible mechanism for the enhanced morphology of the lead halide films by the addition of PbBr2 is proposed based on the growth of a Br-saturated lead iodide solid solution. Furthermore, iodine vacancies, identified by X-ray photoelectron spectroscopy, decreased as the ratio of PbBr2 increased. Finally, an electrical analysis of the solar cells was performed by using a PN heterojunction model, revealing that structural defects, such as iodine vacancies and grain boundaries, are the main contributors to the degradation of the performance of pure PbI2-based solar cells (including high leakage, low stability, and high hysteresis), which was significantly improved by the addition of PbBr2. The solar cell fabricated at x = 0.3 in air showed excellent stability and performance. The device lost merely 20% of the initial efficiency of 4.11% after 1500 h without encapsulation. This may be due to the dense microstructure and the reduced structural defects of lead halides formed at x = 0.3.