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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.

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.

We investigated the relationship between the fine structure of spin-coated conductive polymer poly(3,4-ethylenedioxythiphene):poly(styrene sulfonate) (PEDOT:PSS) films and the photovoltaic performance of PEDOT:PSS crystalline-Si (PEDOT:PSS/c-Si) heterojunction solar cells. Real-time spectroscopic ellipsometry revealed that there were two different time constants for the formation of the PEDOT:PSS network. Upon removal of the polar solvent, the PEDOT:PSS film became optically anisotropic, indicating a conformational change in the PEDOT and PSS chain. Polarized Fourier transform infrared attenuated total reflection absorption spectroscopy and Raman spectroscopy measurements also indicated that thermal annealing promoted an in-plane π-conjugated Cα = Cβ configuration attributed to a thiophene ring in PEDOT and an out-of-plane configuration of -SO3 groups in the PSS chain with increasing composition ratio of oxidized (benzoid) to neutral (quinoid) PEDOT, Iqui/Iben. The highest power conversion efficiency for ...

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.