Effects of doping at the ppm level in Simple n+p-homojunction organic photovoltaic cells

Abstract

a b s t r a c tThe effects of doping at concentrations at the ppm level in organic photovoltaic cells were clarified using simple n þ p-homojunctions. With doping from 0 to 10 ppm, the fill factor increased due to the appearance of majority carriers. From 10 to 100 ppm, the photocurrent density increased due to an increase in the built-in potential, i.e., the formation of an n þ p-homojunction. The photocurrent was increased by a factor of 1.3 by directly doping the photoactive co-deposited layer with acceptor molecules at a concentration of 100 ppm.

Hall Effect in Bulk‐Doped Organic Single Crystals

“…Recently, the effects of the ultralow doping of vacuum‐deposited organic semiconductor films have been reported . We previously reported the effects of doping at concentrations down to 1 ppm in organic photovoltaic cells with simple pn ‐homojunctions . We believe that doping organic single crystals without grain boundaries is necessary to precisely clarify the nature of the doping effects.…”

“…Although research has long examined impurity doping in thin organic semiconductor films, no one has attempted to dope impurities into the bulk of single crystals of organic semiconductors. In this study, we successfully dope impurities into the bulk of rubrene single crystals by combining the homoepitaxial growth and our original ultraslow co‐evaporation techniques . Furthermore, this approach enables us to investigate the doping effects and dopant‐induced structural disorder.…”

Doping for Controlling Open-Circuit Voltage in Organic Solar Cells

“…The large V OC change of 0.16 V in total suggested that energy levels near the D/A interface were greatly shifted by the addition of MoO 3 and Cs 2 CO 3 in the H 2 Pc layer. Noteworthy point is that most of the previous reports of the doping in OSCs added a p-type dopant in donor layers to enhance the hole conductivity. − However, we found that n-type doping in the donor layer increased the V OC .…”

“…Doping, addition of trace amount of p-type and n-type impurities, is the central technology in the inorganic solar cells. It has also been studied in the field of OSCs. − The doping effects in the previous reports of OSCs can be roughly classified into three topics: conductivity enhancement, ,, trap filling, and dipole moment formation . Liu et al have reported that the addition of a molecular p-type dopant tetrafluoro-tetracyanoquinodimethane (F4TCNQ) into solution-processed bulk heterojunction (BHJ) OSCs increased the hole conductivity and improved the short-circuit current ( J SC ) and fill factor (FF) .…”

Dawn of Organic Single Crystal Electronics-Hall Effect in Doped Organic Single Crystals

“…We combined the growth technique of rubrene organic single crystals which show the band-conduction [1,2] with the research group's original ultra-slow deposition technique of one billionth of a nano meter (10 -9 nm) per second, which includes a rotating shutter having aperture of the ratio reaching 1:1000 (Figure 1) [3,4] and have succeeded in producing the 1ppm doped organic single crystal and in detecting the Hall effect signal [5]. It was found that the doping efficiency of organic single crystal is 24%, which is close to that of silicon single crystal.…”