Electron-selective quinhydrone passivated back contact for high-efficiency silicon/organic heterojunction solar cells

Effect of Thermal Annealing on the Charge Carrier Selectivity of Ultra‐Thin Organic Interface Dipoles in Silicon Organic Heterojunction Solar Cells

“…[ 58–65 ] In particular, organic molecules with a strong permanent dipole moment can change the band alignment at the interface and, thus, the charge carrier selectivity by modifying the concentration of charge carriers in the vicinity of the electrode contact. In the past dipole materials such as 8‐hydroxyquinolinolato‐lithium (Liq), [ 66,67 ] polyethyleneoxide (PEO), [ 68 ] poly[(9,9‐bis(30‐( N , N ‐diethylamino)propyl)‐2,7‐fluorene)‐alt‐2,7‐(9,9‐dioctylfluorene)] (PFN), [ 69 ] perylene diimide (PDIN), [ 70 ] buckminsterfullerene (C 60 ) doped by tetrabutylammoniumiodide (TBAI), [ 71 ] poly[4,8‐bis(2‐ethylhexyloxyl)benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl‐alt‐ethylhexyl‐3‐fluorothieno[3,4‐b]thiophene‐2‐carboxylate‐4,6‐diyl] (PTB7)‐based conjugated polyelectrolytes, PTB7‐NBr and PTB7‐NSO3, [ 72 ] quinhydrone (QHY), [ 73 ] and branched polyethylenimine (b‐PEI) [ 41 ] were applied as ultra‐thin interfacial layers to form electron‐selective contacts. In addition, the amino acid l ‐histidine was investigated as an electron‐selective contact, enabling promising contact properties.…”

Understanding of Molecular Contribution of Quinhydrone/Methanol Organic Passivation for Improved Minority Carrier Lifetime on Nanostructured Silicon Surface

“…After 180-min passivation in QHY/MeOH (Figure 7c), the scan shows highly severe molecular aggregations compared with that of pure BQ (Figure 7e). The QHY/MeOH passivation is known to induce positive surface charge on the Si surface by the strong dipole moment of the SQ molecule producing Si surface band-bending (field effect passivation) [24]; therefore, the molecular aggregation after excess dipping time weakened the molecular dipole moment [12]. This is because, although dipole moment is a vector quantity produced by charge asymmetry within molecules, random stacking of molecules would encourage π-π interaction between stacked molecules, thereby reducing charge asymmetry and consequently producing a weaker dipole moment within the molecular layer [27].…”

“…al. successfully demonstrated that QHY/MeOH passivation is highly effective to fabricate cost-effective and low-temperature processable dopant-free Si/organic heterojunction solar cells [12].…”

Solution‐Processed Electron‐Selective Contacts Enabling 21.8% Efficiency Crystalline Silicon Solar Cells

“…Metal fluorides (e.g., lithium fluoride and magnesium fluoride), metal carbonates (e.g., cesium carbonate, potassium carbonate, and calcium carbonate), low work function metals (e.g., calcium and magnesium), and organic polymers (e.g., quinhydrone, poly(ethylene oxide), C 60 pyrrolidine tris‐acid, and phenyl‐C 61 ‐butyric acid methyl ester) have been proven to be effective ETLs. [ 22–29 ] The other approach to realize effective electron‐selective contact is to passivate the surface state density at c‐Si/metal interface. For example, some metal oxides (e.g., titanium oxide, magnesium oxide, and tantalum oxide) and metal nitrides (e.g., titanium nitride, titanium oxynitride, and tantalum nitride) can form effective electron‐selective contacts with n‐type c‐Si even if they do not have low work function.…”

“…Metal fluorides (e.g., lithium fluoride and magnesium fluoride), metal carbonates (e.g., cesium carbonate, potassium carbonate, and calcium carbonate), low work function metals (e.g., calcium and magnesium), and organic polymers (e.g., quinhydrone, poly(ethylene oxide), C 60 pyrrolidine tris-acid, and phenyl-C 61 -butyric acid methyl ester) have been proven to be effective ETLs. [22][23][24][25][26][27][28][29] The other approach to realize effective electron-selective contact is to passivate the surface state density…”