This study investigates near-infrared (IR) phototransistors utilizing hybrid systems of indium gallium zinc oxide (IGZO) and PbSe colloidal quantum dots with distinct surface ligands and diameters. Tetrabutylammonium iodine (TBAI)-modified quantum dot film exhibits an insulative property and abundant traps. Under 1064 nm light illumination, the devices with TBAI-modified quantum dots achieve a high photoresponsivity of 2.63 × 104 A/W, a high detectivity of 1.15 × 1014 Jones, and an exceptional photosensitivity exceeding 107 in transient response. In contrast, the mercaptopropionic acid (MPA)-modified quantum dot film shows higher conductivity and fewer traps, resulting in faster relaxation of photon-induced carriers and a rapid response speed of the devices with MPA-modified quantum dots. Additionally, the device with MPA-modified quantum dots exhibits better air stability compared to the TBAI-modified device. The impact of quantum dot size on device performance was explored, revealing that the device based on larger PbSe quantum dots exhibits superior performance under 1550 nm illumination, with the photoresponsivity and detectivity reaching 4.96 × 105 A/W and 2.88 × 1015 Jones, respectively. This research provides valuable insights and suggests promising applications for IGZO-PbSe quantum dot hybrid systems in the development of high-performance near-IR photodetectors with customizable properties.
The lead chalcogenide quantum dots with a size smaller than 3 nm and good chemical stability were difficult to synthesize due to the poor chemical reactivity of commonly used phosphine-free chalcogen and lead sources. Here we report the synthesis of small and surface passivated PbSe quantum dots (QDs) by addition of SnCl2 as the nucleation promoting agent and PbCl2 as the in situ passivation agent. Common PbCl2 (dissolved in oleylamine, oleic acid, and 1-octadecene) and elemental Se (dissolved in oleylamine) were used to synthesize small PbSe QDs by addition of SnCl2 to promote the fast nucleation of PbSe nanocrystals. The sizes of the PbSe QDs are between 3 and 8 nm and are tunable by controlling the ratio of PbCl2/SnCl2 and the reaction time. High photostability of PbSe QDs approved by the XPS analysis and photoluminescence spectra of PbSe QDs was also achieved by the in situ formation of thin halide adlayers on the surface of QDs. This new method is green with accessible raw materials and simple in situ passivation scheme and will enable the broader utilization of PbSe QDs in ambient conditions in many optoelectronic applications.
Sisi Liu,Meng Wang,Xiong Yu,Hao Li,Haifei Lu,Xiaoyan Wen,Ming-Yu Li,Jianbing Zhang
Infrared (IR) solar cells are potential optoelectronic devices for boosting the power conversion efficiency (PCE) of conventional photovoltaics (such as pervoskite and silicon solar cells) by broadening the utilization range of the sunlight spectrum to short-wavelength infrared region. PbSe colloidal quantum dots (QDs) are one of the optimal candidates for IR solar cells because of their tunable bandgap in the IR region and flexible solution processibility. At present, the best PbSe QD IR photovoltaics generally adopt ZnO as an electron transport layer (ETL). However, the intrinsic drawbacks and surface defects of ZnO can potentially deteriorate the PCE of devices. Herein, Ti 3 C 2 T x , a representative 2D transition carbide, is combined with sol-gel ZnO to develop a new hybrid ETL for fabricating high-performance IR solar cells. This combination effectively suppresses the defects within ZnO by forming new bondings and simultaneously enhances the crystalline of ZnO film. Meanwhile, the introduction of Ti 3 C 2 T x into ZnO film accelerates the transport and collection of photo-generated carriers by constructing a new electron transport pathway. Consequently, compared to the bare devices, the infrared PCE of PbSe QD solar cells increases by 19.5% to 1.04%. These results demonstrate that this hybrid ETL can offer a bright approach for developing high-performance optoelectronic devices.
Xiaoyu Zhang,Yu Zhang,Hua Wu,Long Yan,Zhenguang Wang,Jun Zhao,William W. Yu,Andrey L. Rogach
We explore two strategies to improve the performance of hybrid solar cells fabricated using poly(3-hexylthiophene) (P3HT) and colloidal PbSe nanocrystals, which have reached a 1 sun power conversion efficiency of 2.9%. Using an atomic passivation strategy towards inorganic ligand-capped nanocrystals, the electron mobilities of PbSe quantum dot films are improved from 1.95 × 10−6 cm2 V−1 s−1 to 1.15 × 10−5 cm2 V−1 s−1. Employing ultrasmall PbSe nanocrystals allows us to adjust their bandgaps towards the type II heterojunction with P3HT, thus achieving efficient charge separation and transfer between the polymer/inorganic constituents. The device performance dropped to half after 10 days' storage, and the P3HT/PbSe interface was found to play a primary role in this efficiency degradation.
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