| 학회 | 한국재료학회 |
| 학술대회 | 2021년 봄 (05/12 ~ 05/14, 광주 김대중컨벤션센터) |
| 권호 | 27권 1호 |
| 발표분야 | 특별심포지엄 6. 탄소중립과 태양광산업 심포지엄-오거나이저: 김진혁(전남대), 손창식(신라대) |
| 제목 | Efficient, stable silicon tandem cells enabled by anion-engineered wide-bandgap perovskites |
| 초록 | Perovskite photovoltaic technology has advanced substantially, with the present record efficiency for single-junction devices reaching ＞ 25%. One of the most promising strategies for commercializing these devices is to apply a perovskite top cell in tandem with a Si bottom cell to reach ultrahigh efficiency beyond the Shockley-Queisser limit for single-junction devices. The ideal band gap for the tandem configuration is ~1.67 to 1.75 eV for the top cell and 1.12 eV for the bottom cell, which, fortuitously, is the Si band gap. The band gap of perovskites can be tuned by (partial) replacement of iodine anions with bromine or chlorine. However, the replacement of I with Br by more than 20%, which is necessary to enlarge the band gap to ~1.7 eV, leads to stability issues under illumination through phase separation that forms I-rich and Br-rich structures. One approach to stabilize the perovskite is to create a two-dimensional (2D) phase in which sheets of [PbX6]−2 octahedra are separated by an excess number of long-chain (or aromatic) molecules that act as a passivation agent. Common long-chain or aromatic molecule-based 2D additives include n- butylammonium iodide (n-BAI) and phenethylammonium iodide (PEAI). Most of the recent studies have focused on the cation components of the 2D additives rather than focusing on the anions. We developed a 2D-3D mixed wide band gap (1.68 eV) perovskite using a mixture of thiocyanate (SCN) with the more conventional choice, iodine. Through a careful application of atomic resolution transmission electron microscopy, we demonstrated that electrical and charge transport properties as well as the physical location of 2D passivation layers can be controlled with anion engineering of the 2D additives. Moreover, we can use this approach to extend light stability and to improve device performance. For a perovskite device, we achieved a PCE of 20.7% that retained ＞ 80% of its initial efficiency after 1000 hours of continuous illumination in working conditions. For a monolithic 2T perovskite/Si tandem solar cells, the champion 2T tandem device achieved a PCE of 26.7%.[1] [1] Shin et al. Science 368, p. 155 (2020). |
| 저자 | Byungha Shin |
| 소속 | Department of Materials Science and Engineering |
| 키워드 | perovskite; tandem solar cells; 2D additives |
