https://scholarworks.unist.ac.kr/handle/201301/87 2026-04-04T11:26:36Z https://scholarworks.unist.ac.kr/handle/201301/89995 Title: Exceeding 2.2 V Open-Circuit Voltage in Perovskite/Organic Tandem Solar Cells via Multi-Functional Hole-Selective Layer Author(s): Son, Jung Geon; Ameen, Shahid; Kim, BongSoo; Kim, Dong Suk; Kim, Jin Young Abstract: Perovskite/organic tandem solar cells (POTSCs) are gaining attention due to their potential to surpass the Shockley-Queisser limit through the reduction of thermalization losses. However, wide bandgap perovskite solar cells (WBG PSCs), which function as top cells of POTSCs, still suffer from significant open-circuit voltage (VOC) loss, which limits the efficiency improvement of POTSCs. Here, we report a multi-functional hole-selective layer (mHSL) via blending two functionalized molecules (4-(3,6-diiodo-9H-carbazol-9-yl)butyl)phosphonic acid (36ICzC4PA) and (4-(3,6-dimethoxy-9H-carbazol-9-yl)butyl)phosphonic acid (36MeOCzC4PA). The blending of the two highly aggregating molecules demicellizes to form a uniform and high-coverage mHSL, which plays multiple roles of (i) providing the homogeneous surface potential of the HSL, (ii) extracting hole efficiently, (iii) enhancing the crystallinity of the perovskite on mHSL, and (iv) suppressing both lattice strain and phase segregation. Thus, it maximizes the VOC in POTSCs. Implementing mHSL on WBG PSCs enables a power conversion efficiency (PCE) of 18.85% with a notable VOC of 1.366 V. When applied to fabricated POTSCs, the PCE reached 24.73% (certified 24.19%) with a record-high VOC and fill factor (FF) of 2.216 V and 84.07%, respectively. Furthermore, encapsulated POTSCs exhibit excellent photostability, retaining 80% of their initial PCEs after maximum power point (MPP) tracking under 1-sun illumination in ambient conditions for 305 hours. In addition, unencapsulated POTSCs demonstrate notable thermal stability, retaining 82% of their initial PCEs after exposure to 65℃ in N2 conditions for 500 hours. 2025-02-11T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/89984 Title: High Open-Circuit Voltage in Perovskite/Organic Tandem Solar Cells with Multi-Functional Hole-Selective Layer Author(s): Son, Jung Geon; Ameen, Shahid; Kim, BongSoo; Kim, Dong Suk; Kim, Jin Young 2025-05-04T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/89975 Title: High-Efficiency Perovskite-Based Tandem Solar Cells Author(s): Kim, Jin Young 2025-07-01T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/89946 Title: High-efficiency Perovskite based Tandem Solar Cells with High Open-circuit Voltage Author(s): Kim, Jin Young Abstract: Perovskite/organic tandem solar cells (POTSCs) offer a promising approach to sur passing the Shockley-Queisser limit by minimizing thermalization losses. However, the efficiency of POTSCs is hindered by substantial open-circuit voltage (VOC) losses in wide bandgap per ovskite solar cells (WBG PSCs), which serve as the top cells. In this work, a multi-functional hole-selective layer (mHSL) was developed by blending two functionalized molecules, 36ICzC4PA and 36MeOCzC4PA. This blend prevents aggregation, forming a uniform and high-coverage mHSL that improves hole extraction, enhances perovskite crystallinity, and suppresses both lattice strain and phase segregation, thereby maximizing VOC. As a result, WBG PSCs achieved a PCE of 18.85% with a VOC of 1.366V, when integrated into POTSCs, the PCE reached 24.73% (certified 24.19%). Compared to POTSCs, perovskite/perovskite tandem solar cells (PPTSCs) offer superior voltage matching and minimized energy losses due to their favorable bandgap alignment. Additionally, their high crystallinity and effective defect passivation contribute to enhanced carrier transport and reduced interfacial recombination, further improving efficiency and long-term stability. These ad vantages make PPTSCs a strong candidate for next-generation photovoltaics. In this presentation, I will discuss our recent results and their implications for future solar cell technologies. 2025-11-06T15:00:00Z