Study on Photovoltaic Performance of Cu₂O_Chitosan Composite Thin Film Solar Cell

Study on Photovoltaic Performance of Cu₂O_Chitosan Composite Thin Film Solar Cell

Thet Thet Mon Dept. of Physics Hinthada University Myanmar

Yin Maung Maung Dept of Physics Mandalay University Myanmar

Thann Thann Win Dept. of Physics

Mandalay University of Distance Education Myanmar

Abstract Cuprous oxide thin film (Cu2O) was prepared on conducting glass support (indium tin oxide ITO coated glass) by spin coating method and was subsequently annealed at 300°C. The structure and surface morphology of the Cu2O thin film was determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The Cu2O_Chitosan thin film was prepared by Spin Coating method. Cu2O_Chitosan thin film was studied by scanning electron microscopy (SEM). The open- circuit voltage (Voc), short-circuit current (Isc) and solar power

acetyl content of the polymer. Chitosan is a non-toxic, biodegradable polymer of high molecular weight and is very much similar to cellulose, a plant fiber. The only difference between chitosan and cellulose is the amine (-NH2) group in the position C-2 of chitosan instead of the hydroxyl (-OH) group found in cellulose.

1. EXPERIMENTAL DETAILS

   conversion efficiency were obtained from the Cu2O_Chitosan A. Preparation of the Cu2O Thin Films

   thin film solar cell. Photovoltaic study revealed that Cu2O_Chitosan thin film exhibited higher efficiency as compared to the Cu2O thin film.

   Keywords Cuprous Oxide; Open-Circuit Voltage; Short_ Circuit Current; Composite;

   1. INTRODUCTION

      Copper (I) oxide or cuprous oxide is the inorganic compound with the formula Cu2O. Cuprous oxide is a promising material with potential applications in solar energy conversion [1]. Cuprous oxide is a p-type semiconductor

      Firstly, 2 ml of 2-methoxyethanol was added to 1 g of cuprous oxide. Then the solution was stirred by heat magnetic stirrer with 720 rpm at 100ºC to get homogeneous solution. After that, indium tin oxide glass substrates were cleaned. The solution was deposited onto ITO coated glass-substrate by spin coating method with 1000 rpm for 30 s. After the spin coating process, the sample was annealed at 300ºC for 1 h. The crystal structure of the film was studied by X -rays diffractometer (XRD) and the crystallite sizes were calculated. The surface morphology of the film was examined by scanning electron microscopy.

      having a direct band gap of 2 eV [2,3,4] which make it very B. Preparation of the Cu2O_Chitosan Composite Thin Film

      suitable for solar applications. It forms a cubic structure with lattice parameter of 4.27Å [5]. Organic materials are inexpensive, easily processable and functionality can be tailored by molecular design and chemical synthesis. The source of chitin in the nature is very wide as well as cellulose source. Chitin could be found in marine animals such as fish and crustacean shell. Chitin is a white, hard, inelastic, nitrogenous polysaccharide found in the exoskeleton as well as in the internal structure of invertebrates. The waste of these natural polymers is a major source of surface pollution in coastal areas. Chitin and chitosan were waste products of the crabbing and shrimp canning industry. Chitosan is a very simple substance. It is derived from chitin, a polysaccharide that is found in the cell wall of fungi and also in the exoskeleton of crustaceans, They are then being processed by removing the shell from shellfish such as shrimp, lobster, crabs etc. Chitosan is a semi crystalline polysaccharide that unlike many biodegradable polymers, is insoluble in water at neutral pH. Chitosan is a fiber-like substance and a homopolymer of ß-(14)-linked N-acetyl-D-glucosamine. The actual difference between chitin and chitosan is the

      1 g of chitosan was dissolved in 100 ml of 1% acetic acid solution under magnetic stirring. When the solution was homogeneous, 1 g of cuprous oxide (Cu2O) was added to the solution. Then, the solution was stirred by magnetic stirrer with 700 rpm to obtain the Cu2O_Chitosan homogeneous solution. Using spin coating method, the sample was deposited onto ITO coated glass. Next, the thin layer was annealed at 300°C for 1 hour. Finally, the Cu2O_Chitosan composite thin film was obtained. Then, XRD, SEM and I-V analysis were performed.

   2. RESULT AND DISCUSSION

A. XRD Analysis

Fig 1 showed the XRD spectrum of Cuprous Oxide thin film at annealing temperature 300 ºC. According to the XRD profile, including the dominant peak (111) and seven peaks of Cu2O of [(110), (111), (200), (211), (220), (221) and (310)]

were clearly observed. The average crystallites size of

Cuprous Oxide thin film was found to be 40.89 nm. It was also observed that the lattice parameter of the Cu2O thin film was well matched to the literature value 4.27Ã… of Cu2O [5].

The average crystallite size of the Cu2O thin film was 40.89 nm. The XRD pattern of the Cu2O_Chitosan composite thin film at annealing temperature 300°C was shown in Fig 2.The characteristic crystalline peak at around 2 = 20 corresponds to nanosized chitosan and similar to[6]. There are six other peaks [(110), (111), (200), (211), (220), and (310)]

(111)

corresponding to the standard XRD pattern. All peaks of cuprous oxide matched well with the standard cubic cuprite structure. The crystallite size of dominant peak (111) plane of cuprous oxide was 36.44 nm. And The average crystallite size was found to be 46.00 nm.

432

Intensity(Counts)

288

(110)

(200)

(211)

(220)

(221)

(310)

144

0

(110)

(111)

(200)

(211)

(220)

(221)

(310)

78-2076> C uprite – C u2O

10 20 30 40 50 60 70

T wo-T heta (deg)

Fig 1 XRD Profile of the Cu2O thin film at 300ºC

Fig 4 showed the SEM image of the Cu2O_Chitosan composite thin film. The morphology of the Cu2O_Chitosan composite thin film was observed using scanning electron microscope (SEM). From SEM image, the sample surface was not seemed to be uniform but fairly smooth, and some porous structures were found. It was observed to be more porous than the Cu2O thin film.

C. Comparison of the I_V Characteristics of the Cu2O Thin Film and Cu2O_Chitosan Thin Film Solar Cells

The solar cells were illuminated through the side of the ITO

coated glass substrates, and the illuminated areas were measured to be 1 cm2 each. The solar cells with ITO coated glasses structure provided power conversion efficiency () and fill factor (Ff). The photocurrents were observed under illumination and the ITO coated glass structures showed characteristic curves of short-circuit current and open-circuit voltage. Fig 5 showed the I_V characteristic of the Cu2O/ITO thin film. Fig 6 showed the I-V characteristics of the Cu2O_Chitosan composite thin film. Comparative facts of photovoltaic parameters of Cu2O and Cu2O_Chitosan composite thin film solar cells were also listed in Table 1 and 2.

0.035

0.030

Photocurrent (mA)

0.025

0.020

0.015

ISC = 0.0315 mA

Im = 0.0231 mA

100oC

0.010

VOC

= 2.8189 V

Fig 2 XRD pattern of the Cu2O_Chitosan composite thin film

B. Investigation of the Cu2O Thin Film by SEM

0.005

0.000

Vm = 2.0657 V

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Cell Vopltage (V)

Fig 3 showed the SEM image of the Cu2O thin film and the average grain size was examined to be 1.6 µm.

0.035

0

0

0