Polymer Schottky Junction

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CdS Decorated Al Doped ZnO Nanorod/Polymer Schottky Junction Ultraviolet-Visible Dual Wavelength Photodetector Saurab Dhar, Pinak Chakraborty, Tanmoy Majumder, and Suvra Prakash Mondal ACS Appl. Nano Mater., Just Accepted Manuscript • DOI: 10.1021/acsanm.8b00551 • Publication Date (Web): 06 Jun 2018 Downloaded from http://pubs.acs.org on June 7, 2018

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ACS Applied Nano Materials

CdS Decorated Al doped ZnO Nanorod/Polymer Schottky Junction Ultraviolet-Visible Dual Wavelength Photodetector Saurab Dhar, Pinak Chakraborty, Tanmoy Majumder and Suvra Prakash Mondal* Department of Physics, National Institute of Technology, Agartala, India -799046. *Corresponding Author’s email: [email protected] and [email protected]

Abstract Ultraviolet and visible dual wavelength photosensing has been observed using inorganic-organic Schottky junction. Photodetectors were fabricated by depositing DMSO modified PEDOT:PSS conducting polymer on CdS decorated Al-doped ZnO nanorod arrays. A prominent dual wavelength photosensitivity has been observed at λ ~380 nm and λ ~500 nm with fast response and recovery time (~ 20ms) even at zero external bias. The maximum device performance was obtained at -5.0 V external bias with external quantum efficiency (EQE) ~55864% and ~12590% ; responsivity (Rλ) ~171 and 50 A/W;

detectivity

(Dλ) ~ 2.6×1011 and

7.7×1010 jones,

corresponding to the wavelengths ~ 380 nm and 500 nm, respectively. To protect from ambient atmosphere and moisture environment, the device was sealed with polydimethylsiloxane (PDMS) polymer. PDMS encapsulated device demonstrated excellent photosensing behavior under water environment. Keywords: ZnO nanorods, CdS, PEDOT:PSS, Photodetector, Schottky junction

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1. Introduction Ultraviolet (UV)-visible dual wavelength photodetectors are very much attractive for several important applications, like broad wavelength emission detection, environmental and biological research1-3. Heterojunction made with high and low band gap semiconductors is a common approach for broadband photodetection3-8. One dimensional (1D) ZnO nanostructures such as nanowires, nanorods and novel metal electrodes (Au, Ag, Pt, Ni) contacts have been studied extensively for UV photodetector application due to high band gap of ZnO (~3.2 eV), superior carrier mobility, simple device geometry, low dark current, fast response and recovery time and high quantum efficiency9-14. Several research works have been focused on the improvement of optoelectronic properties of ZnO by doping several metal impurities such as Ga, Al, In etc15-20. Al doped ZnO is particularly important for optoelectronic device applications due to its easy synthesis process, high electrical conductivity and superior optical properties

21-24

. Although,

doping enhances the carrier mobility and UV absorption, band gap engineering is required for UV-visible photoabsorption of ZnO. Combination of ZnO with other narrow band gap semiconductor (for example ZnSe Cu2O, CdSe, CdS ) has been proven to be feasible for dual wavelength detection25-28. Among these materials, CdS has been attracted much attention because of excellent visible photo-absorption, similar lattice structures and type-II band alignment. 29-32 On the other hand, instead of using expensive metal electrodes, ZnO nanorod/conducting polymer Schottky junction has been studied as UV photodetectors with superior external quantum efficiency, responsivity and detectivity33-35. Fabrication of such kind of inorganicorganic heterojunction is cost effective compared to high vacuum deposition of metal electrodes. Recently, poly 3,4-ethylenedioxythiophene: polystyrene sulfonate (PEDOT:PSS) has been 2 ACS Paragon Plus Environment

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studied as an alternative of metal electrodes due to its superior carrier mobility, large work function (5-5.2 eV) and excellent transparency (above 90%) in a wide spectral range (250 nm to 800 nm)36,37. More importantly, the electrical conductivity of such polymer can be modulated in wide range (0.5 to 1000 S/cm2) by doping with various solvents like ethylene glycol, poly ethylene glycol, dimethyl sulfoxide (DMSO) etc. 38-40 In this article, UV-visible dual wavelength photodetectors were fabricated by using CdS decorated ZnO nanorods-polymer Schottky junction. The photoresponse properties of Schottky junction photodetectors was enhanced by Al doping in ZnO. The photodetector parameters such as external quantum efficiency (EQE), detectivity, responsivity, response and recovery time have been studied. The degradation of such inorganic/organic heterojunction photodetector was tested in ambient air and under water after encapsulation with polydimethylsiloxane (PDMS) polymer. 2. Experimental methods 2.1 Fabrication of Aluminum doped ZnO nanorods (AZO) Al doped ZnO nanorods (AZO NRs) were synthesized on fluorine doped tin oxide (FTO) coated glass substrate by hydrothermal process similar to ZnO nanorods growth. The details experimental process for ZnO NRs growth on FTO substrates was reported elsewhere34, 40-43. At first, a thin seed layer was deposited by spin coating of ZnO nanoparticle solution (seed solution) prepared from 0.01M zinc acetate dehydrate (Sigma Aldrich, 98%) dissolved in 50ml 2propanol. For the hydrothermal growth of nanorods, ZnO nanoparticle seeded FTO substrates were dipped into a Teflon lined stainless steel autoclave containing equimolar (0.05M) solution of zinc nitrate (Sigma Aldrich, 98%) and HMTA (Sigma Aldrich, 99%). For Al doping 2.43 mM of Aluminum nitrate (Alfa Aesar 98%) was also added in the previous solution. The



hydrothermal reaction temperature was maintained at 95°C for 4 hour. Al doped ZnO NRs were washed thoroughly in de-ionized water (DI) followed by annealing at 400°C for 1 hour. 2.2. Growth of CdS decorated AZO coreshell NRs by chemical bath deposition method Deposition of cadmium sulfide (CdS) layer on AZO NRs was done by a simple chemical bath deposition process. At first, 0.025 M of CdAc2 (Loba, 98%), 0.1 M of ethylenediamine (Merck, 99%), and 0.1 M of thiourea (Merck, 99%) were dissolved in 100 ml DI water and the solution was heated at 60°C temperature. When the transparent solution was turned into yellow color, AZO NRs were dipped for 10 mins. 2.3. Device fabrication The photodetector devices were fabricated by spin coating PEDOT:PSS polymer (procured from Sigma Aldrich) on CdS coated AZO NRs at a spin speed 2000 rpm. To increase the conductivity of PEDOT:PSS polymer, DMSO was added at various volume ratio. The maximum conductivity was obtained at DMSO/PEDOT:PSS volume ratio 3:4 (conductivity~ 24 S/cm)27. All samples were heated at 120°C for 10 min to evaporate the solvents. Electrical contacts were made using two small copper wires connected from bottom FTO and top PEDOT:PSS electrodes by using a tiny amount of conducting silver paste (Ted Pella Inc, USA). The active device area for all samples was 0.12 cm2. To protect PEDOT:PSS polymer from ambient atmosphere and moisture, the photodetector devices were sealed with PDMS polymer (Dow Corning, Sylgard 184). Electrical measurements were carried out using a source meter (B2912A, Agilent, USA). The photosensing properties of the samples were tested using a broadband light source (Science Tech, Canada), and a monochromator (Science Tech, Canada).


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3. Results and Discussions Fig. 1(a) shows top view scanning electron micrographs of AZO NRs arrays grown on FTO coated glass substrates with average diameter 200 nm. Al doping in ZnO NRs was confirmed by energy dispersive X-ray spectroscopy study (EDS) (Supporting Information, Fig. S1). The SEM micrograph of CdS coated ZnO nanorods is presented in Fig.1(b). The surface modification and increase of diameter of Al-ZnO nanorods arrays have been observed after deposition of CdS (diameter~350 nm). Fig. 1(c) represents the plane view bright field TEM micrograph of CdS decorated Al doped ZnO nanorods. The TEM micrograph clearly demonstrated the formation of CdS shell of average thickness ~ 50 nm. The selected area electron diffraction pattern (SAED) presented in Fig. 1(d) reveals that the deposited CdS shell is polycrystalline in nature and the dominant diffraction patterns in the micrograph are indexed as (111), (220), and (311) planes of cubic CdS. Crystalline behavior of pristine ZnO NRs, AZO NRs and CdS/AZO core-shell NRs was confirmed by X-ray diffraction study (Supporting Information, Fig. S1). ZnO as well as AZO NRs are highly crystalline with hexagonal wurtzite structure and grown along (002) direction34 (Fig. S1(b), Supporting Information). Interestingly, the (002) peak of AZO NRs has been shifted to lower 2Ɵ, which is attributed to Al doping in ZnO NRs (Inset of Fig. S1(b), Supporting Information)44. On the other hand, the deposited CdS shells are also highly crystalline with cubic phase44. The broadening in XRD peak for CdS was also observed due to the formation CdS nanoparticles, which corroborates our SEM micrographs. To estimate the carrier concentration in undoped and Al doped ZnO NRs, Mott-Schottky (M-S) measurements were carried out under dark condition (Fig. S1(d), Supporting Information). The donor concentration (Nd) of ZnO NRs was found to be 1.5×1019 cm-3 and after Al doping Nd was calculated as 2.3×1020 cm-3. The 5 ACS Paragon Plus Environment


improvement of carrier density is attributed to the doping effect of aluminum atoms in ZnO nanorods 45. Optical absorption of ZnO, AZO and CdS/AZO NRs were carried out in the wavelength rage 300 nm to 700 nm . The UV-visible absorption spectra of ZnO NRs and AZO NRs revealed characteristic absorption edge near 385 nm associated with the band edge transition of ZnO (Supporting Information, Fig. S2). Interestingly, absorption edge of CdS/AZO NRs has been extended up to visible spectrum (~550 nm) due to the presence of CdS shell46. To study the photodetection properties, following three samples were fabricated (i) FTO/ZnO NRs/DMSO modified PEDOT:PSS (denoted as S1) (ii) FTO/AZO NRs/DMSO modified PEDOT:PSS (denoted

as S2) and (iii) FTO/CdSAZO NRs/ DMSO modified PEDOT:PSS

(denoted as S3). In the above samples DMSO was mixed with PEDOT:PSS of volume ration 3:4. The schematic device structure of the sample is presented in Fig. 2(a). Fig. 2(b) and 2(c) show the photograph of FTO substrates before and after chemical etching. The schematic device structure and actual photograph of sample S3 after PDMS encapsulation are depicted in Fig. 2(d) and 2(e), respectively. The current density vs. voltage (J-V) characteristics of sample S2 and S3 under dark condition are plotted in figure 3(a). The J-V characteristics of sample S1 is shown at the inset of Fig. 3(a). All samples demonstrated good rectification behavior confirming the formation of Schottky junction between ZnO NRs and PEDOPT:PSS polymer. More importantly the sample S3 showed higher rectification ratio (J/Jo ~343.5 at ±5V) compared to S2 (~64.9 at ±5V). For better understanding the junction properties at nanorod-polymer interfaces, half wave rectification behavior was demonstrated for device S2 and S3 using a sine and square wave input


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signal with frequency range 10 Hz to 100 Hz (Supporting Information, Fig. S3). The half-wave rectification behaviors using sine and square wave at a typical frequency ~50Hz are plotted in the Fig. 3(b) and 3(c), respectively. Interestingly, sample S3 demonstrated excellent half wave rectifying behavior with minimal waveform deformation of the output signal, which indicates outstanding junction formation at nanorod/polymer interface. Fig. 4(a) shows transient photoresponse (J-t) plot of sample S1 under illumination of intensity 80 mW/cm2 at 0 V bias. The transient photoresponse of S2 and S3 samples at identical conditions are plotted in Fig.4(b). The change in photocurrent (JLight-JDark) for S1, S2 and S3 samples are found to be 0.0274, 11.06 and 27.01 µA/cm2, respectively. Interestingly the photocurrent of S3 increases 985 times and S2 increases 400 times compared to S1 sample. In our study, S3 device demonstrated higher photocurrent at zero bias due to excellent Schottky junction formation and visible photoabsorption. In the following discussion, the photodetector properties of S3 sample has been studied in details. To demonstrate the wavelength selectivity of the photodetector external quantum efficiency (EQE) was estimated using the following equation34,40 (%) =

× ×

× 100………………………….. (1)

Where, Jλ and Pλ are photocurrent density (mA/cm2) and light intensity (mW/cm2) at particular wavelength λ (nm). Fig. 5(a) shows EQE (%) vs. λ plot for S3 device without any external bias. The EQE vs λ plot has a maximum peak at UV region (EQE~ 3.10% at 380 nm) and a maximum peak at visible region (EQE~1.3% at 500nm). Such dual wavelength photodetection is attributed to the combined effect of CdS shell and AZO nanorods structure. The carrier transport mechanism at CdS/ZnO heterojunction under illumination of light is presented at inset of Fig.



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5(a). Due to the formation of type-II band alignment between CdS and ZnO, photogenerated electrons and holes can be easily transferred to the electrodes under illumination. To demonstrate UV-visible dual wavelength photodetection, photoresponse characteristics was measured at wavelength ~ 380nm and 500nm using a mechanical chopper with frequencies 5, 10 and 20Hz in absence of any external bias. The transient photoresponse at 20 Hz frequency is presented in Fig.5(b). The transient photoresponse with 5 and 10 Hz copper frequencies is shown in supporting information Fig S4. Interestingly, even at zero external bias, the photocurrent transients demonstrated repeated fast response and recovery under on-off incident light. The estimated rise(from 0-90%) and decay(100-10%) times at 380nm are ∼22 ms and ∼20 ms and at 500nm are ∼22 ms, and ∼17 ms, respectively. Fig. 6(a) demonstrates the EQE vs. λ plot of S3 sample at -5V bias. It has been observed that, at higher sample bias, EQE vs λ plot is identical with zero sample bias. Interestingly, at higher bias (-5V), the EQE at 380nm and 500 nm are found to be ~55864% and ~12590%, respectively. It can be mentioned that, in case of Al doped ZnO NRs, the only EQE peak was observed at 380 and the maximum EQE value was found to be ~ 33366% (Fig. S5, Supporting Information). The EQE greater than 100% is attributed to trap assisted carrier transport phenomenon at nanorod/polymer Schottky junction10,34,40.

The

responsivity and detectivity have been calculated by using the following equations22 and plotted in Fig 6(b).

=

& =

− … … … … … … … … . . (2) !"# '2()

… … … … … … … … … … . . (3)


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Where JLight and JDark denotes the current density at light and dark, Popt is the intensity of incident light at a particular wavelength λ and q is the charge of electron. The vs λ and & vs λ plots clearly demonstrated that, the operation range of the photodetectors varies from UV to mid visible range (300-550 nm). The peak values for responsivity were found to be 171 A/W and 50 A/W corresponding to the wavelengths 380 nm and 500 nm, respectively. On the other hand, the maximum value of detectivity was found to be 2.6×1011 jones at 380 nm and 7.7×1010 jones at 500 nm wavelength. Fig. 6c shows the transient photocurrent (J-t plot) of S3 at -5V bias under illumination of wavelength 380nm and 500 nm. The photocurrent change (JLight-JDark) at 380 nm and 500 nm were found to be 56.39 and 23.29 mA/cm2, respectively. Although, CdS decorated AZO NRs/DMSO modified PEDOT:PSS schottky junction photodetectors demonstrated fast response and recovery time, superior responsivity and detectivity, however, the degradation is the major issue of such kind of inorganic/organic based heterojunction devices. To protect PEDOT:PSS polymer from ambient air and moisture, we have sealed the devices with PDMS polymer and photodetector properties was tested in water under illumination of white light of intensity 100mW/cm2. Fig. 7(a) represents current density vs. time (J-t) plots before and after dipping in water. Fig. 7(b) represents the photograph of the device during testing under water medium. Interestingly, the device showed identical behaviors in water medium. However, the small decrease in current due to UV absorption by water. The comparison of photodetector parameters such as photocurrent, operating voltage operating wavelength, responsivity, response time and recovery time of similar kind of ZnO NRs based devices are listed in Table 1. Our result clearly demonstrated superior photodetector performance compared to others ZnO nanorod based devices.



Conclusion: In summary, we have fabricated inorganic-organic Schottky junction photodetector using CdS decorated Al doped ZnO nanorods and DMSO modified PEDOT:PSS conducting polymer. Photodetector properties such as external quantum efficiency (EQE), responsivity (Rλ) and detectivity (Dλ) have been studied under zero bias and -5.0V external bias. Our photodetector (Sample S3) demonstrated dual wavelength detection at ~380 nm and λ ~500 nm with fast response and recovery time. The maximum detector performance was obtained at -5.0 V external bias. The photodetector parameters at UV region (λ ~ 380 nm) were found to be EQE ~55864%, Rλ ~171 A/W and Dλ ~ 2.6×1011 Jones. On the other hand, the values of EQE, Rλ and Dλ at visible region (λ ~500 nm ) was obtained as 12590% , 50 A/W and 7.7×1010 Jones, respectively. To prevent degradation from moisture environment, the photodetector was sealed with PDMS polymer. PDMS encapsulated device demonstrated excellent photodetection behavior in underwater of about 3cm depth. Our present study demonstrated the possibility of UV-Visible dual wavelength photosensing using a solution grown inorganic-organic Schottky junction for all weather photodetection. Acknowledgements This present research work was partially funded by CSIR Extramural Research Grant, Sanction No. 03(1316)/14/EMR-II dated 16/04/ 2014, Government of India. We acknowledged the central research facility (CRF) of NIT Agartala for UV-VIS-NIR spectroscopy and XRD measurements. Supporting Information Available: The EDS spectrum, XRD plots, Mott-Schottky plots, UV-Vis absorption spectra, Half-wave rectification behaviors at 10, 15, 20, 50, 75 and 100 Hz signal frequencies of S2 & S3 samples, transient photocurrent of S3 sample and EQE plot of S2 device are presented in the supporting document.


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Figures:

1µm

1µm

Fig.1: Top view SEM micrograph of (a) Al doped ZnO nanorods and (b) CdS decorated Al doped ZnO nanorods, (c) TEM micrograph of CdS decorated Al doped ZnO nanorod coreshell structure and (d) typical SAED pattern of CdS shell deposited on ZnO nanorods .


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Figure 2: (a) Schematic diagram of the sample (b) Optical photographs of FTO substrate, (c) Chemically etched patterned FTO substrate, (d) Schematic diagram of the device after PDMS encapsulation and (e) Optical photograph of the actual PDMS encapsulated device.



5 2

Current density (mA/cm )

10

Current Density(mA/cm2)

4

10

3

10

2

10

100 10 1 0.1

S1 Dark

0.01 1E-3

1

-1.0

10

-0.5

0.0

0.5

1.0

Voltage (V)

0

10

S2 dark S3 dark

-1

10

-2

10

-3

10

-4

10

-6 -5 -4 -3 -2 -1

0

1

2

3

4

5

6

Voltage(V) 4

Reference Signal

S3

S2

50Hz

Voltage(V)

3

2

1

0

-1

-2

-3 -0.10

-0.05

0.00

0.05

Time(s) Reference

S2

S3

50Hz

3

2

Voltage(V)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 18 of 24

1

0

-1

-2

-3 -0.10

-0.05

0.00

0.05

Time(s)

Fig.3: (a) J-V plots of samples S2 and S3 in semi-logarithmic scale. Semi-logarithmic J-V plot of sample S1 is shown at inset. Half-wave rectification performance of S2 and S3 samples using reference signal with (b) square wave and (c) sine wave. 18 ACS Paragon Plus Environment


S1

0.00 ON

-0.01 -0.02 -0.03 OFF

-0.04

Current Density(µA/cm2)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Current Density(µA/cm2)

Page 19 of 24

0

ON

-20 OFF

-40

-60

S3 S2

-80 100

150

200

250

100

Time(s)

150

200

250

Time(s)

Fig.4: Transient response of the photocurrent (J-t) under 0V bias of (a) S1 and (b) S2 and S3 samples under illumination of broadband light source of intensity 80 mW/cm2.



Normalized Current Density

3.5 3.0 2.5

EQE%

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

2.0 1.5 1.0 0.5 0.0 300

400

500

600

700

1.0

Page 20 of 24

380 nm

ON

0.5 OFF

0.0 0.70

0.75

0.80

0.85

0.90

Time(s) 1.0

500 nm ON

0.5 0.0

OFF

0.70

Wavelength(nm)

0.75

0.80

0.85

0.90

Time(s)

Fig. 5(a): External quantum efficiency vs. wavelength plot of sample S3 under 0 V bias. Carrier transport process under illumination is shown schematically at the inset. (b) The transient photoresponse plots (J-t) of S3 sample at wavelength 380 nm and 500 nm with chopping frequency 20 Hz.


Page 21 of 24

4

6x10

4

5x10

EQE%

4

4x10

4

3x10

4

2x10

4

1x10

400

500

600

700

Wavelength(nm)

11

250

3.0x10

200

2.4x10

150

1.8x10

100

1.2x10

50

6.0x10

11

11

11

10

0 300

400

500

Detectivity (Jones)

0 300

Responsivity(A/W)

0.0 700

600

Wavelength(nm) Current Density(mA/cm2)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


380nm

-10

500nm

-20 -30 ON

-40 -50

OFF

-60 -70 0

50

100

150

200

Time(s)

Fig.6: (a) External quantum efficiency (EQE) % vs wavelength plot for sample S3 at -5 V. (b) Rλ vs λ and Dλ vs λ plots of S3 sample at -5 V bias and (c) Transient photocurrent (J-t) of device S3 at -5 V bias under light of wavelength 380 nm and 500 nm.


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Current Density(mA/cm2)


0

Air Under water)

ON

-100

-200

-300 OFF

-400 50

100

150

200

Time(s)

Fig.7: (a) Transient photocurrent (J-t plot) of device S3 in air and under water (3 cm from surface) at bias -5 V. The photoresponse was measured under illumination of broadband light of intensity 100mA/cm2 and (b) Photograph of sample S3 during measurement under water.


Page 22 of 24

Page 23 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Table 1: Comparison of the photodetector parameters such as photocurrent, operating voltage operating wavelength, responsivity, response time and recovery time of ZnO NRs based devices ZnO Photodetector type

Photocurr ent

Operat ing voltage

Operati Responsi ng vity wavelen gth

Respons Recover e time y time

Refe renc es

Indium doped ZnO/PEDOT:PSS

400% increase

1V

532nm

---

---

---

47

PEDOT:PSS/ZnO: S

2.8 ×10−4A

3V

---

---

---

---

48

ZnO nanorod/PEDOT:P SS

674 µA

5V

256nm

5.046 A/W

Several sec

Several mins

49

Single crystal ZnO/PEDOT:PSS

3.5×10−9 A

0V

370nm

0.3A/W

---

---

37

ZnO@CdS/PEDO T:PSS/Au

3.65 x106 A

at 0V

400500nm

---

20 ms

40ms

50

ZnO Nanorod/GQD/PE DOT:PSS

~15mA/cm

-1V

340nm

36 A/W

---

---

34

Ag/CdS/ZnO core shell/Ag

183 nA

4V

468nm

---

26ms

2.1 ms

51

Al-doped ZnO NR arrays

240 µA

10V

------

4.19 A/W 15 sec

52 sec

52

Al-doped ZnO@CdS core shell/PEDOT:PSS

56.39 mA/cm2

5V

380nm

171 A/W

22ms

20ms

This work

Al-doped ZnO@CdS core shell/PEDOT:PSS

23.29 mA/cm2

5V

500nm

50 A/W

22ms

17 ms

This work

2



Graphical Abstract


Page 24 of 24

Polymer Schottky Junction

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