PSS Heterojunction Research Articles

Efficient crystalline Si/organic hybrid heterojunction solar cells

AbstractEfficient crystalline silicon (c‐Si) heterojunction solar cells with conductive poly(ethylene dioxythiophene):poly(styrene sulfonate)(PEDOT:PSS) and graphene oxide (GO) are demonstrated using device structures of c‐Si/GO/PEDOT:PSS/Ag and c‐Si/PEDOT:PSS:GO composite/Al. The power‐conversion efficiency η increased from 8.76 to 9.27% under illumination of AM1.5 100 mW/cm2 simulated solar light by adjusting the GO thickness for the n‐Si/GO/PEDOT:PSS heterojunction solar cells. η also increased to 10.6% for the n‐Si/PEDOT:PSS:GO composite devices by adjusting the GO mixing concentration.The GO addition to conductive PEDOT:PSS suppressed electron recombination and/or promoted the hole current at the anode. The soluble PEDOT:PSS:GO composite is promising as a hole‐transporting transparent conducting layer for c‐Si/organic junction photovoltaic applications. The uniform coating of poly(3‐hexylthiophene‐2,5‐dily) (P3HT) and PEDOT:PSS on textured hydrophobic c‐Si wafer was observed by the electrospray deposition. The textured related enhancement of the device performance is demonstrated (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Chemical mist deposition of graphene oxide and PEDOT:PSS films for crystalline Si/organic heterojunction solar cells

AbstractThe chemical mist deposition of graphene oxide (GO) and poly(3,4‐ethylenedioxythiophene):poly(stylenesulfonate) (PEDOT:PSS) were investigated on the crystalline silicon (c‐Si) substrate for the n‐type c‐Si/organic heterojunction solar cells. The uniform coating of GO flake with an average size of 1‐5 μm was obtained on the hydrophobic c‐Si wafer using deionized water as a solvent. The GO layer thickness could be controlled from a monolayer to a few tens of nanometres by vary‐ ing mist deposition time. The c‐Si/GO/ PEDOT:PSS heterojunction solar cells shows the efficiency improved from 8.75 to 9.27% with insertion of GO flakes a the PEDOT:PSS and c‐Si interface owing to the enhanced suppression of electron recombination and/or promotion of hole current at the anode. Furthermore, the CMD was also applied to coat conductive PEDOT:PSS films on the textured c‐Si. The η of 7.75% was obtained with a short‐circuit current of 34.22 mA/cm2, a open‐circuit voltage of 0.46 V, and a fill factor of 0.48. These findings imply that CMD is a promising method for the uniform deposition of both nanomaterials (GO) and conjugated polymer for the c‐Si/ organic heterojunction solar cells (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Electrospray Deposition of Poly(3-hexylthiophene) Films for Crystalline Silicon/Organic Hybrid Junction Solar Cells

The electrospray deposition (ESD) of poly(3-hexylthiophene) (P3HT) films for use in crystalline silicon/organic hybrid heterojunction solar cells on a crystalline silicon (c-Si) wafer was investigated using real-time characterization by spectroscopic ellipsometry (SE). In contrast to the nonuniform deposition of products frequently obtained by spin-coating, a uniform deposition of P3HT films was achieved on flat and textured hydrophobic c-Si wafers by adjusting the deposition conditions. Similar findings were also obtained for the deposition of conductive poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on P3HT. The c-Si/P3HT/PEDOT:PSS heterojunction solar cells exhibited efficiencies of 4.1 and 6.3% on flat and textured c-Si wafers, respectively. These findings suggest that ESD is a promising method for the uniform deposition of P3HT and PEDOT:PSS films on flat and textured hydrophobic substrates.

Highly efficient crystalline silicon/Zonyl fluorosurfactant-treated organic heterojunction solar cells

We demonstrate a highly efficient hybrid crystalline silicon (c-Si) based photovoltaic devices with hole-transporting transparent conductive poly-(3,4-ethlenedioxythiophene):poly(styrenesufonic acid) (PEDOT:PSS) films, incorporating a Zonyl fluorosurfactant as an additive, compared to non additive devices. The usage of a 0.1% Zonly treated PEDOT:PSS improved the adhesion of precursor solution on hydrophobic c-Si wafer without any oxidation process. The average power conversion efficiency η value was 10.8%-11.3%, which was superior to those of non-treated devices. Consequently, c-Si/Zonyl-treated PEDOT:PSS heterojunction devices exhibited the highest η of 11.34%. The Zonyl-treated soluble PEDOT:PSS composite is promising as a hole-transporting transparent conducting layer for c-Si/organic photovoltaic applications.

Fabrication of large area high density, ultra-low reflection silicon nanowire arrays for efficient solar cell applications

High density vertically aligned and high aspect ratio silicon nanowire (SiNW) arrays have been fabricated on a Si substrate using a template and a catalytic etching process. The template was formed from polystyrene (PS) nanospheres with diameter 30–50 nm and density 1010/cm2, produced by nanophase separation of PS-containing block-copolymers. The length of the SiNWs was controlled by varying the etching time with an etching rate of 12.5 nm/s. The SiNWs have a biomimetic structure with a high aspect ratio (∼100), high density, and exhibit ultra-low reflectance. An ultra-low reflectance of approximately 0.1% was achieved for SiNWs longer than 750 nm. Well-aligned SiNW/poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) heterojunction solar cells were fabricated. The n-type silicon nanowire surfaces adhered to PEDOT:PSS to form a core-sheath heterojunction structure through a simple and efficient solution process. The large surface area of the SiNWs ensured efficient collection of photogenerated carriers. Compared to planar cells without the nanowire structure, the SiNW/PEDOT:PSS heterojunction solar cell exhibited an increase in short-circuit current density from 2.35 mA/cm2 to 21.1 mA/cm2 and improvement in power conversion efficiency from 0.4% to 5.7%. Open image in new window

Half wave rectification of inorganic/organic heterojunction diode at the frequency of 1 kHz

An inorganic/organic vertical heterojunction diode has been demonstrated with p-type Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) deposited by spin coating on n-type Ga-doped ZnO (GZO) thin films. Transparent conducting GZO thin films are deposited on glass substrate by rf-magnetron sputtering. Electrical properties of GZO thin films are investigated depending on the processing temperatures. The resistivity, mobility and carrier concentration of the GZO thin films deposited at processing temperatures of 500°C are measured to be about 3.6×10−4Ω cm, 23.8cm2/Vs and 7.1×1020cm3, respectively. The root mean square surface roughness of the GZO thin films is calculated to be ~0.9nm using atomic force microscopy. Current-voltage characteristics of the n-GZO/p-PEDOT:PSS heterojunction diode present rectifying operation. Half wave rectification is observed with the maximum output voltage of 1.85V at 1kHz. Low turn-on voltage of about 1.3V is obtained and the ideality factor of the n-GZO/p-PEDOT:PSS diode is derived to be about 1.8.