Chlorophyll-Based Organic–Inorganic Heterojunction Solar Cells

5 years ago

Chlorophyll-Based Organic–Inorganic Heterojunction Solar Cells

Shin-ichi Sasaki, Xueqi Fu, Mengzhen Li, Kotowa Sakai, Toshitaka Ikeuchi, Xiao-Feng Wang, Gang Chen, Hitoshi Tamiaki, Osamu Kitao, Wenjie Zhao, Yue Li

Solid-state chlorophyll solar cells (CSCs) employing a carboxylated chlorophyll derivative, methyl trans-32-carboxypyropheophorbide a, as a light-harvesting dye sensitizer chlorophyll (DSC) deposited on mesoporous TiO2, on which four zinc hydroxylated chlorophyll derivatives were spin-coated for hole transporter chlorophylls (HTCs), are described. Key parameters, including the effective carrier mobility of the HTC films, as determined by the space charge-limited current method, and the frontier molecular orbitals of these DSCs and HTCs, as estimated from cyclic voltammetry and electronic absorption spectra, suggest that both charge separation and carrier transport are favorable. The power conversion efficiencies (PCEs) of the present CSCs with fluorine-doped tin oxide (FTO)/TiO2/DSC/HTCs/Ag were determined to follow the order of HTC-1>HTC-2>HTC-3>HTC-4, which coincided perfectly with the order of their hole mobilities. The maximum PCE achieved was 0.86 % with HTC-1. The photovoltaic devices studied herein with two types of chlorophyll derivatives as dye sensitizers and hole transporters provide a unique solution for the utilization of solar energy with a view to truly realizing “green energy”. Naturally sensitive: Solid-state chlorophyll solar cells can be used that employ a carboxylated chlorophyll derivative, methyl trans-32-carboxypyropheophorbide a, as a light-harvesting dye sensitizer chlorophyll (DSC) deposited on mesoporous TiO2, upon which four zinc hydroxylated chlorophyll derivatives are spin-coated as hole transporter chlorophylls (HTCs; see figure).

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/chem.201701858