Cathode Interlayer Based on Naphthalene Diimide: A Modification Strategy for Zinc-Oxide-Free Inverted Organic Solar Cells
Perylene diimide with ammonium oxide as a terminal group (named PDIN-O) is a well-known cathode interlayer in conventional-type organic solar cells (OSCs). Since naphthalene diimide exhibits a lower LUMO level than perylene diimide, we chose it as a core to further control the LUMO level of the mate...
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Veröffentlicht in: | ACS applied materials & interfaces 2023-05, Vol.15 (17), p.21324-21332 |
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Sprache: | eng |
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Zusammenfassung: | Perylene diimide with ammonium oxide as a terminal group (named PDIN-O) is a well-known cathode interlayer in conventional-type organic solar cells (OSCs). Since naphthalene diimide exhibits a lower LUMO level than perylene diimide, we chose it as a core to further control the LUMO level of the materials. Small molecules (SMs) produce a beneficial interfacial dipole by the end of ionic functionality at the side chain of naphthalene diimide. With the active layer based on a nonfullerene acceptor (PM6:Y6BO), the power conversion efficiency (PCE) is enhanced by utilizing SMs as cathode interlayers. We discovered that the inverted-type OSC with naphthalene diimide with oxide as a counteranion (NDIN-O) shows poor thermal stability, which can cause irreversible damage to the interlayer–cathode contact, leading to poor PCE (11.1%). To overcome the disadvantage, we introduce NDIN-Br and NDIN-I with a higher decomposition temperature. An excellent PCE of 14.6% was achieved with the device based on NDIN-Br as an interlayer, which is almost the same as the PCE of the ZnO-based device (15.0%). The device based on NDIN-I without the ZnO layer exhibits an improved PCE of 15.4%, which is slightly higher than the ZnO-based device. The result offers a replacement of the ZnO interlayer, which is necessary to carefully manage the sol–gel transition by annealing temperatures as high as 200 °C and leading to low-cost manufacture of OSCs. |
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ISSN: | 1944-8244 1944-8252 |
DOI: | 10.1021/acsami.3c02181 |