International Seminar on Science and Technology, ISSTEC 2009, Yogyakarta, Indonesia

Problems in Determining Two Diodes Equivalent Circuit Parameters of Organic Solar Cell Using Reverse Bias Characteristic

Kuwat Triyana, Sholihun, Budi Prabowo Soewondo, Timothy Siahaan and Kamsul Abraha

Physics Department, Faculty of Mathematics and Natural Sciences, Gadjah Mada University
Sekip Utara BLS 21, Yogyakarta 55281, Indonesia

e-mail: triyana@ugm.ac.id, lion_avs@yahoo.com

Abstract. An equivalent circuit parameters of heterojunction bilayer copper phthalocyanine/perylene organic solar cell for one diode model have been accurately calculated in our previous work. The calculation has been performed based on reverse bias characteristic using an assumption that there will be a linear profile near the breakdown voltage on the current-voltage (J-V) curve. The confirmation has been clarified by comparing the curve from this model with the curve obtained from the experiment. The result gives a very good fitting to the current density-bias voltage curve in that we cannot distinguish the curve from our model with the one from the experimental data. However, since we still have problem in describing the physics mechanism based in our previous work, we are going to continue our investigation through the recent work. For instant, it is still difficult for us to determine whether the shunt resistance is a result from the bulk or from the interface. In the recent study, we found that problems came up when we applied this approach to the two diodes model such as the negative value of shunt resistance (Rp), while the value of series resistance (Rs) exceed the value of Rp. These problems contrary to the reality that Rp must be positive and the value of Rs is always smaller than Rp. Hopefully, the problems presented in this paper can give useful information to the development of the research to increase the efficiency of organic solar cell in the future.

Keywords: two diodes equivalent circuit model, photovoltaic device, reverse bias characteristic

Seminar Nasional: Kecenderungan Baru Fisika dan Kependidikannya, 2008, Malang, Indonesia

Metode Komputasi Koefisien Rekopling Simbol 3n-J (n 2) Melalui Kaitan Rekursif Aljabar dan Beberapa Nilai Eksak serta Penerapannya

Sholihun1+, Pekik Nurwantoro1¨, Kuwat Triyana2*
1 Grup Penelitian Fisika Komputasi
2 Laboratorium Fisika Material dan Elektronika

Jurusan Fisika, Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas Gadjah Mada, BLS 21, Yogyakarta 55281, Indonesia

E-mail: +lion_avs@yahoo.com, ¨pekik@ugm.ac.id, *triyana@ugm.ac.id

Intisari: Telah dibuat metode komputasi simbol 3n-j (n 2) melalui kaitan rekursif aljabar dan telah dilakukan perhitungan untuk beberapa nilainya. Simbol 3n-j muncul dalam mekanika kuantum ketika terjadi kopling antara n+1 momentum sudut. Misalnya, simbol 6-j muncul ketika terjadi kopling tiga momentum sudut dan simbol 9-j muncul ketika terjadi kopling empat momentum sudut. Kasus ini mempunyai posisi yang cukup penting dalam dinamika kuantum, khususnya untuk sistem partikel banyak. Perhitungan secara analitik sulit dilakukan, bahkan tidak mungkin dilakukan karena banyaknya produk faktorial yang terkandung dalam persamaan yang terlibat. Sehingga perhitungan numerik sangat diperlukan untuk memecahkan permasalahan tersebut. Dalam makalah ini akan disajikan metode umum untuk perhitungan simbol 3n-j yang mempunyai bentuk eksplisit dalam ekspresi simbol 6-j. Sehingga ketika nilai simbol 6-j diperoleh maka dengan mudah simbol 3n-j akan diperoleh. Penelitian ini dilakukan dengan metode komputasi melalui kaitan rekursif aljabar, perhitungan secara logaritmik dan menggunakan metode Continued Fraction untuk menyajikan hasil komputasi dalam bentuk pecahan.

Kata kunci: momentum sudut, simbol 3n-j, kaitan rekursif aljabar

Seminar Nasional: Kecenderungan Baru Fisika dan Kependidikannya, 2008, Malang, Indonesia

A Study on Internal Parameters Based on Reverse Bias Characteristic of Organic Photovoltaic Devices and Their Dependency on Intensity of Illumination

Kuwat Triyana1*, Timothy Siahaan2¨, Sholihun3+, Yuyun Irmawati1, Herlina Pratiwi1, Kamsul Abraha1

1Laboratory of Material Physics and Electronics
2 Research Group on Theoretical and Mathematical Physics
3Research Group on Computational Physics

Physics Department, Faculty of Mathematics and Natural Sciences, Gadjah Mada University, BLS 21, Yogyakarta 55281, Indonesia

E-mail: *triyana@ugm.ac.id, ¨timmy_fisika_ugm_99@yahoo.co.id, +lion_avs@yahoo.com

Abstract. Information about internal parameters of organic photovoltaic devices is needed as a guideline in further fabrication of such devices with good performance. In this paper we investigate the current density-voltage characteristic of copper phthalocyanine (CuPc)/3,4,9,10-perylenetetracarboxylic (PTCBI) thin film heterojunction photovoltaic device in seeking such information. It is assumed that the device can be described by the standard one-diode equivalent circuit which is usually used to model inorganic photovoltaic devices. In order to find five parameters included in the model, we use the formula for open circuit voltage and short circuit current and two additional equations from the reverse bias characteristic of the device which is studied. The parameters of the device are found to depend on the illumination intensity. We calculate the parameter's value for each intensity. The result will be used for further study on the device especially as a comparison for the microscopic modeling for the same device.

Keywords: heterojunction, organic photovoltaic device, internal parameters, one diode equivalent circuit model

IEEE International Conference on Semiconductor Electronics, ICSE 2008, Johor Bahru, Malaysia

On the Dependency of Equivalent Circuit Parameters of Heterojunction Bilayer Copper Phthalocyanine/Perylene Photovoltaic Device on Light Intensity based on Reverse Bias Characteristic

Kuwat Triyana1, Timothy Siahaan1 , Sholihun1, Kamsul Abraha1, and
Muhamad Mat Salleh2

1)Physics Department, Gadjah Mada University, BLS 21, Yogyakarta 55281, Indonesia
2)Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia , 43600 UKM Bangi, Selangor, Malaysia

Email: triyana@ugm.ac.id

Abstract. In order to study the dependency of organic photovoltaic device on light intensity, we investigate the current density-bias voltage characteristics of phthalocyanine/perylene thin film heterojunction photovoltaic device under illumination of various intensities. We use the standard one diode equivalent circuit to model the device and calculate the parameters included in the model. In calculating the parameters, we use the formula for short circuit current density and open circuit voltage and consider the reverse bias characteristics of the device, which provides two additional equations from only one additional fitting. Using this approach, we have four equations to determine five parameters. From our calculation, we find that the parameters depend on the intensity of light illumination that subsequently results on the decreasing of the performance of the device. The ideality factor and the photocurrent density is found to be linearly dependent on light intensity. The decreasing of shunt and series resistance when the light intensity increases is also found and, together with the linear-increasing of the value of ideality factor, are suspected to be the source of the decreasing of the device performance.

International Seminar on Science and Technology, ISSTEC 2009, Yogyakarta, Indonesia

A Proof of Dependency of Organic Photovoltaic Device Diode Ideality Factor on Light Intensity Using Linear Approximation near Break-down Voltage Method

Sholihun, Kuwat Triyana, Timothy Siahaan and Budi Prabowo Soewondo

Physics Department, Faculty of Mathematics and Natural Sciences, Gadjah Mada University
Sekip Utara BLS 21, Yogyakarta 55281, Indonesia

e-mail: triyana@ugm.ac.id, lion_avs@yahoo.com

Abstract. In determining photovoltaic device internal parameters, we have compared the result of two assumptions about diode ideality factors (n). First assumption is that n is a generic property of the device, which is independent on light intensity, so that the value of the parameter determined from the data obtained on darkness (without illumination). Second assumption is that n is an intensity-dependent parameter. The calculation of internal parameters is done based on the reverse bias characteristic and used the assumption that there is a linear profile near the breakdown voltage on the current-voltage (J-V) curve. We called this method as Linear Approximation Near Breakdown Voltage (LANBV) method from now on. To find out whether n is independent or dependent on light intensity, we have done curve fitting between the J-V curves obtained from experiment with the curve obtained from each assumption. For the first assumption there is significance deviation between the curves obtained from both conditions. Surprisingly, the second assumption gives a very good fitting to the current density-bias voltage curve in that we cannot distinguish the curve from our approximation with the curve from the experimental data. Finally, we conclude that there is dependency between organic photovoltaic device diode ideality factor and intensity of illumination.

Keywords : photovoltaic device, reverse bias characteristics, LANBV method

Internationam on Mathematics and Natural Sciences, ICMNS 2008, Bandung, Indonesia

A METHOD OF DETERMINATION OF EQUIVALENT CIRCUIT PARAMETERS BASED ON REVERSE BIAS CHARACTERISTIC OF PHOTOVOLTAIC DEVICES

Timothy Siahaan, Kuwat Triyana, and Sholihun

Physics Department, Gadjah Mada University, Yogyakarta Indonesia

E-mail: timmy_fisika_ugm_99@yahoo.co.id and lion_avs@yahoo.

Abstract. Determination of equivalent circuit parameters of photovoltaic devices is very important in studying the performance of such device. In this paper we propose a simple but quite accurate method to determine such parameters by considering the reverse bias characteristic of a photovoltaic devices. Considering the reverse bias characteristic of a photovoltaic device gives four equations for five parameters included in the well known one diode equivalent circuit model, simplifying the computation of the parameters. As an example, we apply this method to determine parameters of a photovoltaic device based on copper phthalocyanine/perylene illuminated with white light at about 100 mW/cm2. The result gives a very good fitting to the current denisty-bias voltage curve in that we cannot distinguish the curve from our approximation with the one from the experimental data.

Keywords: one diode equivalent circuit model, photovoltaic device, current density-voltage characteristics.