Suchergebnisse

Ruddlesden-Popper perovskites (RPPs), consisting of alternating organic spacer layers and inorganic layers, have emerged as a promising alternative to 3D perovskites for both photovoltaic and light-emitting applications. The organic spacer layers provide a wide range of new possibilities to tune the properties and even provide new functionalities for RPPs. However, the preparation of state-of-the-art RPPs requires organic ammonium halides as the starting materials, which need to be ex situ synthesized. A novel approach to prepare high-quality RPP films through in situ formation of organic spacer cations from amines is presented. Compared with control devices fabricated from organic ammonium halides, this new approach results in similar (and even better) device performance for both solar cells and light-emitting diodes. High-quality RPP films are fabricated based on different types of amines, demonstrating the universality of the approach. This approach not only represents a new pathway to fabricate efficient devices based on RPPs, but also provides an effective method to screen new organic spacers with further improved performance. ; Funding Agencies|ERC Starting Grant [717026]; National Natural Science Foundation of China [51472164, 61704077]; 1000 Talents Program for Young Scientists of China; Shenzhen Peacock Plan [KQTD2016053112042971]; Educational Commission of Guangdong Province [2015KGJHZ006, 2016KCXTD006]; Science and Technology Planning Project of Guangdong Province [2016B050501005]; Natural Science Foundation of SZU [000050]; Joint NTU-LiU Ph.D. programme on Materials and Nanoscience; European Commission Marie Sklodowska-Curie Actions [691210]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFOMat-LiU) [2009-00971]; JSPS-NTU Joint Research Project [M4082176]; Ministry of Education Tier 2 [MOE 2017-T2-2-002]; Singapore National Research Foundation [NRF-CRP14-2014-03, NRF-NRFI-2018-04]

Recently, Ruddlesden-Popper perovskites (RPPs) have attracted increasing interests due to their promising stability. However, the efficiency of solar cells based on RPPs is much lower than that based on 3D perovskites, mainly attributed to their poor charge transport. Herein, a simple yet universal method for controlling the quality of RPP films by a synergistic effect of two additives in the precursor solution is presented. RPP films achieved by this method show (a) high quality with uniform morphology, enhanced crystallinity, and reduced density of sub-bandgap states, (b) vertically oriented perovskite frameworks that facilitate efficient charge transport, and (c) type-II band alignment that favors self-driven charge separation. Consequently, a hysteresis-free RPP solar cell with a power conversion efficiency exceeding 12%, which is much higher than that of the control device (1.5%), is achieved. The findings will spur new developments in the fabrication of high-quality, aligned, and graded RPP films essential for realizing efficient and stable perovskite solar cells. ; Funding Agencies|Research Grants Council of the Hong Kong Special Administrative Region, China [11304115]; National Natural Science Foundation of China [51473138]; Joint NTU-LiU Ph.D. programme on Materials and Nanoscience; Swedish Research Council VR [330-2014-6433]; European Commission Marie Sklodowska-Curie action [INCA 600398, 691210]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; Nanyang Technological University [M4080514]; Ministry of Education Academic Research Fund Tier 1 grants [RG101/15, RG173/16]; Ministry of Education Academic Research Fund Tier 2 grants [MOE2014-T2-1-044, MOE2015-T2-2-015, MOE2016-T2-1-034]; Singapore National Research Foundation through the Competitive Research Program [NRF-CRP14-2014]; Marie Sklodowska-Curie Fellowship [2016-02051]