A transparent ultraviolet triggered amorphous selenium p-n junction

Abstract

This paper will introduce a semitransparent amorphous selenium (a-Se) film exhibiting photovoltaic effects under ultraviolet light created through a simple and inexpensive method. We found that chlorine can be doped into a-Se through electrolysis of saturated salt water, and converts the weak p-type material into an n-type material. Furthermore, we found that a p-n diode fabricated through this process has shown an open circuit voltage of 0.35 V toward ultraviolet illumination. Our results suggest the possibility of doping control depending on the electric current during electrolysis and the possibility of developing a simple doping method for amorphous photoconductors.

Characterization of a‐Se p–i–n junction fabricated using bidirectional electrolysis in NaCl(aq)

“…Incorporation of Cl through electrolysis was confirmed by an ION-TOF ToF-SIMS in our recent research [1]. Figure 2 shows the depth profile of the postelectrolysis film (a) which used a-Se as a cathode, which confirms that the signal intensity of Na increased nearly one order of magnitude compared to the pre-electrolysis signal (b).…”

“…For notation, the direction of the applied bias was from Au (A) toward Au (B). [1]. A diode that activates on UV-light illumination was successfully fabricated by using the arsenic-incorporated film on one side and the Cl-incorporated layer on the other.…”

“…Former research proposed that an open-circuit voltage (V OC ) of 0.35 V toward ultraviolet illumination [1]. Although the short-circuit current is at present too small for it to be applied to a solar cell, the transparency of this film enables utilization toward an electrochromic smart glass with variable opacity depending on the intensity of incoming ultraviolet rays from sunlight.…”

Charge transport in pure and stabilized amorphous selenium: re-examination of the density of states distribution in the mobility gap and the role of defects

“…The simple statement c i = C t N i has one more deceptive assumption that N i does not change during transport, that is we neglect trap filling effects. Trap filling effects would mean c i = C t (N i -n i ), which would introduces a nonlinearity into the set of equations written in (1)- (3). Under small signal operation, in which the photoinjected carrier concentration is very small.…”

“…Stabilized amorphous selenium (a-Se) based-multilayer photoconductive structures are currently used in flat panel X-ray imaging detectors (also called flat panel imagers) as well as avalanche solid state imaging devices (see, for example, [1][2][3][4][5]). The direct conversion detector principle is based on an absorbed X-ray photon generating a primary electron, which ionizes the medium and generates many electrons and holes.…”