The Ulsan National Institute of Science and Technology (UNIST) has reported 18.04% power conversion efficiency for a hybrid tandem device bringing together spectrally matched inorganic perovskite and organic bulk heterojunction (BHJ). Researchers say they employed low-temperature solution-processed 2-terminal hybrid solar cell devices for their research work.
Led by Professor Sung-Yeon Jang, the researchers at the School of Energy and Chemical Engineering at the South Korean institute achieved this efficiency level by matching optical properties of front and back cells using CsPbI2Br and PTB7‐Th:IEICO‐4F BHJ as the active materials, they explain and say this is higher than that of single-junction devices, namely 9.21% for the CsPbI2Br and 10.45% for the organic BHJ devices.
Sharing their R&D success story, the researchers say it was possible due to near-optimal absorption spectral match between the 2 sub-cells, and claim that the 18.04% level is 'thus far the highest performance among the reported tandem devices based on perovskite and organic materials'. Researchers further add that the hybrid tandem device demonstrated improvement in the long-term stability under humidity stress, due to hydrophobicity of the organic BHJ back-cell layer.
The 18.04% efficiency confirms the viability of perovskite based solar cells (PSC) technology for transition to commercial-scale manufacture. "In addition, this study rationally suggested the possibility of achieving a PCE of as much as ≈28% in the inorganic perovskite/organic hybrid tandem devices by improving EQE and reducing energy loss in the sub‐cells," explains the team.
The UNIST research has been published in the science journal Advanced Energy Materials.