CuI-based hybrid junction in photovoltaic devices with semitransparent cathode

Abstract

Phone: þ78 314 179 473, Fax: þ78 314 17 464A hybrid inorganic/organic heterojunction formed by p-type cuprous iodide CuI and n-type fullerene C 60 was employed in the archetypal photovoltaic devices. The thickness of the p-CuI layer deposited on a molybdenum oxide (MoO x ) anode buffer was optimized to achieve a higher efficiency, while the thickness of the n-C 60 photoabsorber layer was fixed. In an attempt to obtain semitransparent devices, a trilayer MoO x / metal/MoO x cathode with a BCP underlayer was applied (metal ¼ Ag or Mg, BCP ¼ bathocuproine). The maximum photovoltage of such devices on a PET/ITO substrate was equal to 0.75 V for an average transparency of about 35% over the range of 380-1000 nm. Similar devices having a nontransparent Al cathode in conjunction with an Alq3 underlayer generate photovoltage of 0.82 V (Alq3 ¼ tris-8-hydroxyquinolinato-aluminum), which shows the important effect of hybrid junctions in multilayer organic-based devices. Original Paper 1700186 (4 of 5) V. V. Travkin et al.: CuI-based hybrid junction in photovoltaic devices ß

Thiadiazole Fused Subporphyrazines as Acceptors in Organic Photovoltaic Cells

“…The rectification in the darkness is usually poor, most likely due to compensating (unwanted) contribution of the interactive 'acceptor/Al' junction. [1][2][3]18,19] Under illumination of 100 mW/cm 2 , a photovoltaic effect arises (Figure 2(a-d)), the corresponding parameters are summarized in Table 1. Significant photovoltage generated by the molecular heterojunction can be expected from the large difference between HOMO energy of donor (SubPcH 12 ) and LUMO energy of acceptor (see Figure 1).…”

“…As known, an exciton-blocking material should carefully be adapted for the specific acceptor/cathode pair to avoid substantial energy losses at the interface. [1][2][3]6,8,18,19,22] An indirect argument for this is the lack of correlation between the value of U oc (Table 1) and the LUMO position in acceptor (Figure 1). This is illustrated in Figure 2(f).…”

“…It is interesting to compare the measured parameters with those of the equivalent cells, in which another, wellknown and effective, acceptor is employed, e.g., fullerene. [1,2,4,8,18,22] Therefore, as a reference, we used similarly made cells incorporating a SubPcH 12 /C 60 junction, with the same scheme and layer thickness as in all subporphyrinoid-based cells (Figure 2(e)). …”

“…[13,14] The preparation of the archetypal photovoltaic cell was similar to that previously reported. [18,19] The cell scheme was 'glass/ ITO/MoO x /SubPcH 12 /acceptor/Al', where MoO x is a 10 nm substoichiometric molybdenum trioxide layer (buffer/workfunction modifier, [1,[5][6][7][8]19] see Figure S1), acceptor = SubPzS 3 F 0 , SubPzS 2 F 4 , SubPzS 1 F 8 , SubPcF 12 (or C 60 , see text), and Al is an aluminum top cathode (40 nm). The thickness of a p-type layer (SubPcH 12 ) was 20 nm, the thickness of an n-type (acceptor) layer was 30 nm.…”

“…The thickness of a p-type layer (SubPcH 12 ) was 20 nm, the thickness of an n-type (acceptor) layer was 30 nm. All functional layers were obtained by the thermal evaporation technique, [15,16,18,19] the standard Aldrich ITO-coated glass slides were used as substrates. (Photo-)electrical characterization of the cells with an active area of 0.16 cm 2 was carried out in an inert atmosphere (argon) at the room temperature using a Zolix SS150 solar simulator and a Keithley 4200 SCS parameter analyzer.…”