High‐efficiency Sb₂S₃‐based hybrid solar cell at low light intensity: cell made of synthesized Cu and Se‐doped Sb₂S₃

Abstract

Cu-doped (as p-doped) and Se-doped (as n-doped) Sb 2 S 3 were synthesized from undoped Sb 2 S 3 using a newly developed technique, simple colloidal synthesis method. X-ray diffraction measurements detected no peaks related to any of the Cu and Se compounds in Cu and Se-doped samples. Energy dispersive X-ray analysis, however, confirmed the presence of Cu and Se ions in the doped samples. Diffuse reflectance spectroscopy revealed the optical band gap energy changes because of doping effect, as reported for both the p-type and the n-type material. The valence-band X-ray photoelectron spectroscopy data showed a significant shift in the valence band to higher (Se-doped; +0.53 eV) and a shift to lower (Cu-doped; À0.41 eV) binding energy, respectively, when compared with the undoped sample. We report here on an inexpensive solar cell designed and made entirely of a synthesized material (indium tin oxide/p-doped Sb 2 S 3 + polyaniline (PANI)/amorphous/undoped Sb 2 S 3 + PANI/n-doped Sb 2 S 3 + PANI/PANI/electrolyte (0.5 M KI + 0.05 M I 2 )/Al). The cell has a high efficiency of 8% to 9% at a very low light intensity of only 5% sun, which makes it particularly suitable for indoor applications. As found, the cell performance at the intensity of 5% sun is governed by high shunt resistance (R SH ) only, which satisfies standard testing conditions. At higher light intensities (25% sun), however, the cell exhibits lower but not insignificant efficiency (around 2%) governed by both the series (R S ) and the R SH . Minimal permeability in the UV region (up to 375 nm) and its almost constant value in the visible and the NIR region at low light intensity of 5% sun could be the reasons for higher cell efficiency.

Intrinsic Defect Limit to the Electrical Conductivity and a Two‐Step p‐Type Doping Strategy for Overcoming the Efficiency Bottleneck of Sb2S3‐Based Solar Cells

“…Therefore, to increase the carrier concentration (the electrical conductivity) and improve the performance of Sb 2 S 3 ‐based solar cells, extrinsic doping becomes necessary for passivating the detrimental recombination center defects and producing more carriers. In the past decade, many experiments tried to dope the Sb 2 S 3 to increase the conductivity . However, the efficiency has not witnessed apparent increase (stagnating at 7.5% in the past 5 years).…”

“…In the past decade, many experiments tried to dope the Sb 2 S 3 to increase the conductivity. [6,15,[42][43][44][45] However, the efficiency has not witnessed apparent increase (stagnating at 7.5% in the past 5 years). This means increasing the conductivity of Sb 2 S 3 through the direct doping is quite difficult, which is easy to understand because the extremely low formation energy (high concentration) of dominant intrinsic donor V S2 and acceptor V Sb2 in Figure 5 can restrain the efficient external doping in intrinsic Sb 2 S 3 .…”

Efficient and novel Sb2 S3 based solar cells with chitosan/poly(ethylene glycol)/electrolyte blend

“…For Sb 2 S 3 ‐based hybrid solar cell, 3 different Sb 2 S 3 powders (p‐, undoped‐, and n‐ Sb 2 S 3 ) were synthesized and their detail experimental procedure has been described in previous studies …”

“…Mostly, the thin films that are made from Sb 2 S 3 were derived from solutions depending on whether dye sensitized or photo‐electrochemical solar cells were made . Recently, we reported synthesis for producing amorphous and crystalline, doped and undoped Sb 2 S 3 powders with excellent electronic properties, ie, convenient band gap . Only Mokurala et al synthesized crystalline Sb 2 S 3 nanorods using antimony trichloride, oleylamine, thiourea, hexanethiol acetone, and toluene, by hot‐injection technique and applied it in solar cell .…”

“…The construction of solar cell device consists of a transparent electrode, indium tin oxide (ITO); absorber material, semiconductor Sb 2 S 3 ; conductive polymers PANI and P3HT; layer for electron conduction, TiO 2 ; chitosan (CS)/polyethylene glycol (PEG)/electrolyte blend and aluminum as counter electrode. In the literature, different inorganic and organic hole conducting materials were used . For fabrication of described solar cell, we used polymers P3HT and PANI.…”