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We investigated the chemical mist deposition (CMD) of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on textured crystalline silicon (c-Si) substrate for efficient c-Si/PEDOT:PSS heterojunction solar cells. The Mie scattering observation and differential mobility analysis characterization revealed that the average size of mist particle decreased from 330 to 30–40 nm with increasing the number density and traveling velocity of mist precursor when positive dc bias of 10 kV was applied to the c-Si substrate. The uniform deposition of PEDOT:PSS films was performed on textured c-Si with the increased adhesion by suitably adjusting Vs and substrate temperature. A power conversion efficiency (PCE) of 11.57% was obtained with Jsc of 36.1 mA cm−2, Voc of 0.49 V, and FF of 0.66, when a positive Vs of 10 kV was applied to c-Si substrate. Furthermore, PCE increased to 12.5% with Jsc of 35.6 mA cm−2, Voc of 0.53 V, and FF of 0.67 by adding a 20-nm-thick AR coating layer of molybdenum oxide MoOx (refractive index, n = 2.1) fabricated by CMD using 12 molybdo(VI) phosphoric acid n-hydrate [H3(PMo12O40) · nH2O] as a precursor. These findings imply that CMD using negatively charged mist precursor is a possible method for the uniform deposition of PEDOT:PSS on textured c-Si substrate for efficient c-Si/PEDOT:PSS heterojunction solar cells.

We demonstrate the optical anisotropy of a transparent conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and its effect on the photovoltaic performance of n-type crystalline silicon (n-Si)/PEDOT:PSS heterojunction solar cells. The depth profile of PEDOT/PSS compositional ratio and optical anisotropy depends on the type of polar solvent and/or external DC bias supplied to n-Si substrate during film deposition by spin coating (SC) and chemical mist deposition (CMD). N-Si/PEDOT:PSS heterojunction solar cells with higher PEDOT/PSS compositional ratio near the film surface exhibited better power conversion efficiency η of 12.5% (@2 × 2 cm2) without any light harvesting techniques. In this chapter, the correlation among the optical anisotropy, the depth profile of PEDOT/PSS compositional ratio in conductive polymer PEDOT:PSS, and the photovoltaic performance of n-Si/PEDOT:PSS heterojunction solar cells is demonstrated.

We firstly investigated efficient poly(3,4-ethylenedioxythiophene): poly(styrenesulfonic acid) (PEDOT:PSS)/n-type polycrystalline silicon (p-Si) heterojunction solar cells fabricated by chemical mist deposition (CMD) using a high-pressure H 2 O-vapor-treated p-Si prior to organic film deposition. High-pressure H 2 O vapor treatment of the p-Si efficiently suppressed grain boundary defects and improved carrier transport at the PEDOT:PSS/p-Si interface. Furthermore, compared to spin coated devices, the CMD devices demonstrated a more uniform photovoltaic performance. The power conversion efficiency of the PEDOT:PSS/p-Si heterojunction solar cells was 9.7% with a short-circuit current density of 33.5 mA/cm 2 , an open-circuit voltage of 0.54 V, and a fill factor of 0.53. These findings suggest that CMD with a negatively charged mist precursor provides uniform adhesion of PEDOT:PSS on p-Si, resulting in increased photovoltaic performance.

Flexible printed circuits (FPC) are generally used to assemble electronics units of mobile phones and the other electronics devices. On the recycling of the waste FPC, separation of the layered components in metal substrates, mounted parts and resin films covering printed wire is important for the effective recovery of precious metals and the other elements. However, there are difficulties on their recycle due to their flexible features that prevent to break down themselves against the impaction force of conventional breaking methods. In this study, frequent shearing forces were applied for the waste FPC chips by making use of attrition type milling. The FPC chips were ground and separated into flakes and powders. As results, some elements were selectively separated. 90mass% of Cu was recovered in the flakes on 1mm sieve. On the contrary, almost of Pd was collected in the powder under 1mm sieve.

Recently, there has been considerable interest in organic/c-Si heterojunction solar cells using organic conductive polymer such as poly(3,4-ethylenedioxythiphene):poly(styrenesulfonate) (PEDOT:PSS) that blocks electrons but passes holes. This PEDOT:PSS/c-Si heterojunction works as a photovoltaic device without using p-n junction and TCO layer. η has reached at 10-13% without using textured c-Si, anti-reflection (AR) coating layer. These findings suggest that the PEDOT:PSS/c-Si heterojunctions is a promising for high-efficiency solution-processed solar cells. Thus, we termed this type of solar cell as c-Si heterojunction with organic thin-layers, “HOT” solar cell. In the present paper, we demonstrate the increased η with improved stability for air storage and light exposure of PEDOT:PSS/c-Si heterojunctuon solar cells by removal of PSS matrix from SC PEDOT:PSS thin film using a mixture of organosulfonic acid and organic solvent.

This chapter describes the state of the art of solution-processed, n-type crystalline Si (n-Si) heterojunction with organic thin-layer (HOT) solar cells using conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). A single junction of PEDOT:PSS/n-Si solar cells on a plane n-Si substrate showed a power conversion efficiency (PCE) of 13.3%. Then, the PCE increased to 15.4% by adding an antireflection layer. In addition, the solar cell module using 10 units of series-connected 2 × 2 cm2 (4-in.)-sized PEDOT:PSS/n-Si solar cells exhibited an 0.37 W (7.2 W). Furthermore, PCE increased to 15.8%–18.2% for the front-PEDOT:PSS/n-Si device on textured n-Si substrate using charged mist deposition (CMD) method. In this discussion, we demonstrate the effect of the optical anisotropy of PEDOT:PSS on the photovoltaic (PV) performance of PEDOT:PSS/n-Si heterojunction solar cells, along with the junction property at the PEDOT:PSS/n-Si interface.