Presentation Information
[9a-E201-3]Open-Circuit Voltage Enhancement in PbS Quantum Dot Solar Cells via Atomic Layer Deposition of Metal Oxide Passivation Layers on ZnO Nanowire Surfaces
〇YUYAO WEI1, Xiaoxiao Mi1, Koichi Tamaki1, Takaya Kubo1, Damien Coutancier2, Nathanaelle Schneider2, Jean-Francois Guillemoles2, Haruko Tamegai1, Saemi Takahashi1, Jotaro Nakazaki1, Satoshi Uchida1, Qing Shen3, Hiroshi Segawa1 (1.RCAST Univ. of Tokyo, 2.IPVF CNRS, 3.Univ. of Electro-Communication)
Keywords:
infrared photovoltaics,colloidal quantum dots,ZnO nanowires
PbS quantum dot (QD)/ZnO nanowire (NW) solar cells are one of the promising candidates for solution-processed infrared photovoltaics. However, the open-circuit voltage (Voc) of these devices is typically limited by interface recombination at the ZnO NW/PbS QD heterojunction. To suppress such recombination, we employed the atomic layer deposition (ALD) method, which enables the conformal deposition of ultrathin and uniform metal oxide passivation layers on the high-aspect-ratio surfaces of ZnO NWs, unlike conventional chemical bath deposition and sputtering techniques.PbS QDs with a first excitonic absorption peak at approximately 1.4 μm and a 1.3-μm-long ZnO NW assembly were used to fabricate PbS QD/ZnO NW solar cells (Fig. 1a). Three different metal oxide (Al2O3, TiO2, SnO2) were deposited on the ZnO NW surfaces by ALD method (Fig. 1b). The current-voltage characteristics revealed that the ALD-grown oxides layers effectively passivated surface defects, as evidenced by improvement in Voc (Fig. 1c). Among the investigated oxides, TiO2 (4 nm) achieved the highest Voc of 0.358 V, representing a 20% enhancement compared with the pristine device (0.297 V). This improvement is attributed to the effective suppression of interfacial nonradiative recombination through the reduction of hydroxyl (OH) groups and oxygen-related defects. However, the enhanced Voc was accompanied by a 20% reduction in short-circuit current (Jsc), likely due to parasitic optical absorption and increased charge-transport resistance. In contrast, the Al2O3 (3 nm) and SnO2 (10 nm) provided a more balanced performance, offering moderate Voc enhancement while maintaining Jsc, owing to their higher optical transparency and favorable energy-level alignment.These results highlight the potential of ALD-based interface engineering for PbS QD/ZnO NW photovoltaics and suggest that TiO2 could provide even greater passivation once deposited under optimized conditions.