Low-Noise and Large-Linear-Dynamic-Range Photodetectors Based on Hybrid-Perovskite Thin-Single-Crystals.

Organic-inorganic halide perovskites are promising photodetector materials due to their strong absorption, large carrier mobility, and easily tunable bandgap. Up to now, perovskite photodetectors are mainly based on polycrystalline thin films, which have some undesired properties such as large defective grain boundaries hindering the further improvement of the detector performance. Here, perovskite thin-single-crystal (TSC) photodetectors are fabricated with a vertical p-i-n structure.

Universal Strategy To Reduce Noise Current for Sensitive Organic Photodetectors.

Low noise current is critical for achieving high-detectivity organic photodetectors. Inserting charge-blocking layers is an effective approach to suppress the reverse-biased dark current. However, in solution-processed organic photodetectors, the charge-transport material needs to be dissolved in solvents that do not dissolve the underneath light-absorbing layer, which is not always possible for all kinds of light-absorbing materials developed.

Highly Narrowband Photomultiplication Type Organic Photodetectors.

Filterless narrowband response organic photodetectors (OPDs) present a great challenge due to the broad absorption range of organic semiconducting materials. The reported narrowband response OPDs also suffer from low external quantum efficiency (EQE) in the desired response window and low rejection ratio. Here, we report highly narrowband photomultiplication (PM) type OPDs based on P3HT:PCBM (100:1, wt/wt) as active layer without an optical filter.

Photomultiplication photodetectors with P3HT:fullerene-free material as the active layers exhibiting a broad response.

A series of polymer photodetectors (PPDs) are fabricated based on P3HT as an electron donor and fullerene-free material DC-IDT2T as an electron acceptor. The only difference among these PPDs is the P3HT:DC-IDT2T doping weight ratios from 2 : 1 to 150 : 1. The PPDs with P3HT:DC-IDT2T (100 : 1, w/w) as the active layers exhibit champion external quantum efficiency (EQE) of 28 000% and 4000% corresponding to 390 nm and 750 nm light illumination at -20 V bias, respectively.

Revealing the working mechanism of polymer photodetectors with ultra-high external quantum efficiency.

We report polymer photodetectors (PPDs) with an evident photomultiplication (PM) phenomenon, based on a sandwich structure ITO/PEDOT:PSS/P3HT:PC71BM(100:1)/Al. A similar device structure has been reported in our previous work, showing great potential as a new type of high performance PPD. However, we found more interesting new phenomena from these PPDs.

Improved Performance of Photomultiplication Polymer Photodetectors by Adjustment of P3HT Molecular Arrangement.

A series of photomultiplication (PM)-type polymer photodetectors (PPDs) were fabricated with polymer poly(3-hexylthiophene)-[6,6]-phenyl-C71-butyric acid methyl ester (P3HT-PC71BM) (100:1, w/w) as the active layers, the only difference being the self-assembly time of the active layers for adjusting the P3HT molecular arrangement. The grazing incidence X-ray diffraction (GIXRD) results exhibit that P3HT molecular arrangement can be adjusted between face-on and edge-on structures by controlling the self-assembly time. The champion EQE value of PPDs, based on the active layers without the self-assembly process, arrives at 6380% under 610 nm light illumination at -10 V bias, corresponding to the face-on molecular arrangement of P3HT in the active layers.

Achieving EQE of 16,700% in P3HT:PC71BM based photodetectors by trap-assisted photomultiplication.

We report a trap-assisted photomultiplication (PM) phenomenon in solution-processed polymer photodetectors (PPDs) based on P3HT:PC71BM as the active layer, the maximum EQE of 16,700% is obtained for the PPDs with PC71BM doping weight ratio of 1%. The PM phenomenon is attributed to the enhanced hole tunneling injection assisted by trapped electrons in PC71BM near Al cathode, which can be demonstrated by the transient photocurrent curves and EQE spectra of PPDs with different PC71BM doping ratios. The positive effect of trapped electrons in PC71BM near Al cathode on the hole tunneling injection is further confirmed by the simulated optical field and exciton generation rate distributions in the active layer and the EQE spectra of PPDs with Al(1)/P3HT:PC71BM(100:1)/Al(2) device structure under forward and reverse biases.

Optimization of charge carrier transport balance for performance improvement of PDPP3T-based polymer solar cells prepared using a hot solution.

Polymer solar cells (PSCs), with poly(diketopyrrolopyrrole-terthiophene) (PDPP3T):[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the active layers, were fabricated using solutions of different temperatures. The best power conversion efficiency (PCE) of the PSCs prepared using a hot solution was about 6.22%, which is better than 5.

Trap-assisted photomultiplication polymer photodetectors obtaining an external quantum efficiency of 37,500%.

A smart strategy is reported to obtain photomultiplication (PM) type polymer photodetectors (PPDs) based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) which are commonly used in polymer solar cells. The PPDs with 1 wt % PC61BM exhibit a champion EQE of 37,500% under 625 nm illumination with an intensity of 8.87 μW cm(-2) at -19 V bias.

Simultaneous improvement in short circuit current, open circuit voltage, and fill factor of polymer solar cells through ternary strategy.

We present a smart strategy to simultaneously increase the short circuit current (Jsc), the open circuit voltage (Voc), and the fill factor (FF) of polymer solar cells (PSCs). A two-dimensional conjugated small molecule photovoltaic material (SMPV1), as the second electron donor, was doped into the blend system of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C71-butyric acid methyl (PC71BM) to form ternary PSCs. The ternary PSCs with 5 wt % SMPV1 doping ratio in donors achieve 4.

Enhanced performance of polymer solar cells by employing a ternary cascade energy structure.

We present a route to successfully tackle the two main limitations, low open circuit voltage (Voc) and limited short circuit-density (Jsc), of polymer solar cells (PSCs) based on poly(3-hexylthiophene) (P3HT) as an electron-donor. The indene-C60 bisadduct (ICBA) was selected as an electron acceptor to improve the open circuit voltage (Voc). The narrow band gap polymer poly[(4,8-bis-(2-ethylhexyloxy)-benzo[1,2-b:4,5-b']dithiophene)-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiophene)-2,6-diyl] (PBDTTT-C), as a complementary electron-donor material, was doped into the host system of P3HT:ICBA to form ternary cascade energy structured PSCs with increased Jsc.

Improved efficiency of bulk heterojunction polymer solar cells by doping low-bandgap small molecules.

We present performance improved ternary bulk heterojunction polymer solar cells by doping a small molecule, 2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl] squaraine (DIB-SQ), into the common binary blend of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). The optimized power conversion efficiency (PCE) of P3HT:PC71BM-based cells was improved from 3.05% to 3.

Organic ultraviolet photodetector based on phosphorescent material.

A new type of organic visible-blind UV-PDs is demonstrated by utilizing phosphorescent material Ir(III)bis[(4,6-difluorophenyl)-pyridinato-N, C(2)'] picolinate (FIrpic) as the electron donor and [6,6]-phenyl-C-61-butyricacidmethylester (PCBM) as the electron accepter, respectively. The peak responsivity of the organic UV-PDs is as high as 140 mA/W, corresponding to an external quantum efficiency of about 48%, under 365 nm UV light with an intensity of 0.018 mW/cm(2).