Chunzhi Jiang

Bio: Chunzhi Jiang is an academic researcher from Xiangnan University. The author has contributed to research in topics: Dark current & Photodiode. The author has an hindex of 2, co-authored 3 publications receiving 18 citations.

Lateral Polymer Photodetectors Using Silver Nanoparticles Promoted PffBT4T-2OD:PC61BM Composite

Abstract: The fabrication of lateral polymer photodetectors (L-PPDs) is rarely reported in literature. Unlike vertical photodiode or phototransistor, it would be much more difficult to experimentally improve all of the performance metrics in lateral structure under long channel without compromising any of them. The performance metrics include charge separation, photomultiplication, trapped-charge relaxation, dark current, fast response and so on. In this research, L-PPDs with comparable performance to photodiodes were developed, and the photodetectors have the structure of quartz/Ag-NPs (1 nm)/ PMMA (30 nm)/PffBT4T-2OD:PC61BM (D/A ratio = 1:1.2; 140 nm)/Ag–Ag electrodes. A phase control of BHJ allows effective electrons to be trapped under high PCBM ratio, which simultaneously gives high charge separation and photomultiplication (gain = 161.5 at a current density of 73 mA/cm2). Moreover, photogenerated electrons trapped in active layer can be neutralized by photoinduced holes stored in Ag-NPs, resulting in an obvio...

Ultrahigh photosensitive organic phototransistors by photoelectric dual control

Abstract: Organic phototransistors (OPTs) simultaneously introduce photo-induced holes and electrons into the structure of organic field-effect transistors (OFETs). The memory effect of the minority carrier is the origin of the large dark current and slow response during the light on/off switching, which is detrimental to the OPT performance and cycling stability. In this research, we report a novel OPT working mode by photoelectric dual control. After each light switch, the dark current is erased by the gate voltage in depletion mode which remains unchanged during light off; the photocurrent increases by device converting to accumulation mode when the light is on. In this way, high performance OPTs have been obtained in an FBT-Th4(1,4) : PC61BM (5 : 1) composite film with the structure of Si/SiO2/OTS/FBT-Th4(1,4) : PC61BM/Au electrodes, which shows a broad spectral response (maximum values at zero gate bias: R 1.2 × 105 A W−1, gain 3.7 × 105 and D* 3.18 × 1016 Jones) from 410 to 740 nm (calculated from the transfer curve). The best performance with photoelectric dual control under 0.0031 mW cm−2@405 nm is achieved with an on/off current ratio of 1.0 × 106, response 1.6 × 104 A W−1, gain 5.0 × 104, spectral detectivity 2.3 × 1017 Jones and response time sub-40 ms, which makes the phototransistor a very promising component for light sensing applications.

The mechanism of photogenerated minority carrier movement in organic phototransistors

Abstract: The acceptor phase, which affects the free carrier transport by trapping the photogenerated minority carrier in the active layer, plays an important role in organic phototransistors (OPTs) based on a bulk heterojunction (BHJ). In this work, the FBT-Th4(1,4):PC61BM blend film with high mobility is selected as the active layer to construct the OPT. A model of the action of minority carrier movement on hole transmission is established by using the change rule of device performance under different donor/acceptor ratios. This model is tested and validated using PTB7:PC61BM-based OPT with low mobility. The results show that a continuous transmission channel of photogenerated minority carrier tends to form in the OPT under high concentration doping, which increases the probability that a minority carrier would recombine with the holes, leading to poor device performance. These results can provide practical guidance for the preparation of high-performance OPT devices. The optimized FBT-Th4(1,4) : PC61BM device with a low D/A ratio (∼10 : 1) obtained shows ultrahigh photoelectric detection performance (gain = 4.7 × 105, D* = 1.4 × 1016 Jones).

Recent Progress in Organic Photodetectors and their Applications.

Abstract: Organic photodetectors (OPDs) have attracted continuous attention due to their outstanding advantages, such as tunability of detecting wavelength, low-cost manufacturing, compatibility with lightweight and flexible devices, as well as ease of processing. Enormous efforts on performance improvement and application of OPDs have been devoted in the past decades. In this Review, recent advances in device architectures and operation mechanisms of phototransistor, photoconductor, and photodiode based OPDs are reviewed with a focus on the strategies aiming at performance improvement. The application of OPDs in spectrally selective detection, wearable devices, and integrated optoelectronics are also discussed. Furthermore, some future prospects on the research challenges and new opportunities of OPDs are covered.

Ultrahigh photosensitive organic phototransistors by photoelectric dual control

Abstract: Organic phototransistors (OPTs) simultaneously introduce photo-induced holes and electrons into the structure of organic field-effect transistors (OFETs). The memory effect of the minority carrier is the origin of the large dark current and slow response during the light on/off switching, which is detrimental to the OPT performance and cycling stability. In this research, we report a novel OPT working mode by photoelectric dual control. After each light switch, the dark current is erased by the gate voltage in depletion mode which remains unchanged during light off; the photocurrent increases by device converting to accumulation mode when the light is on. In this way, high performance OPTs have been obtained in an FBT-Th4(1,4) : PC61BM (5 : 1) composite film with the structure of Si/SiO2/OTS/FBT-Th4(1,4) : PC61BM/Au electrodes, which shows a broad spectral response (maximum values at zero gate bias: R 1.2 × 105 A W−1, gain 3.7 × 105 and D* 3.18 × 1016 Jones) from 410 to 740 nm (calculated from the transfer curve). The best performance with photoelectric dual control under 0.0031 mW cm−2@405 nm is achieved with an on/off current ratio of 1.0 × 106, response 1.6 × 104 A W−1, gain 5.0 × 104, spectral detectivity 2.3 × 1017 Jones and response time sub-40 ms, which makes the phototransistor a very promising component for light sensing applications.

Simultaneous Photomultiplication Improvement and Response Acceleration for High-Performance Lateral Polymer Photodetectors Based on Bulk Heterojunction.

Abstract: In organic photodetectors, photomultiplication is mainly originated from interfacial and/or bulk charge traps, which induces slow response due to the slow release of trapped charges and strongly limits the optimization of the overall performance. This study has exhibited a remarkable case that the gain (>1) and response speed of the lateral photodetectors are promoted simultaneously and effectively by increasing the trap ratio. For lateral photodetectors with silver nanoparticles and PDPPBTT:PC61BM bulk heterojunction, the gain increases from 12.7 to 19.8 and the fall time decreases from 313.4 to 172.9 ms as the PC61BM ratio increases from 5:1 to 1:1. The lateral photodetector structure with a long electrode distance has been testified to play the key role for simultaneous promotion compared with vertical photodiodes, allowing the charges to trap well in the PC61BM-rich phase at a high PC61BM ratio and accumulation of multiple built-in electric fields. The long channel distance and silver nanoparticles also effectively restrain the increment of dark current with PC61BM loading, resulting in a high detectivity of 1.7 × 1012 Jones under 0.031 mW cm-2 @ 820 nm. It is of great theoretical and practical value for the high-performance photodetectors with simultaneous high photomultiplication and quick response.