Polarization‐sensitive photodetectors are gaining numerous attention since polarization detection is important in geological remote sensing, atmospheric monitoring, military recon, and medical ...examination. Among various reported photoactive materials for photodetectors, metal halide perovskites have outstanding advantages such as tunable band gaps, excellent optoelectronic properties, and easy fabrication. Moreover, the characteristics of crystal structure anisotropy and controllable growth orientation of perovskite crystals endow the perovskite photodetector with the ability to identify light polarization states. This review outlines the recent research progress of perovskite photodetectors on polarization‐sensitive detection. Firstly, key device parameters of polarization‐sensitive detection are introduced. Then, the recent progress of polarization‐sensitive perovskite detectors in the field of linear and circular polarization is reviewed according to the different principles of polarization response. Finally, the challenges of polarization‐sensitive perovskite photodetector are discussed.
Polarization‐sensitive photodetectors are important in geological remote sensing, atmospheric monitoring, military recon, and medical examination. The review addresses the recent research progress of perovskite photodetectors on polarization‐sensitive detection in terms of key device parameters, linear and circular polarization via different principles of polarization response.
Heating is a knotty factor contributing to device degradation of flexible organic solar cells (FOSCs), and thermal regulation plays a crucial role in the realization of long operational lifetime. ...Herein, a passive cooling strategy for stable FOSCs is proposed by boosting the optical‐thermal radiative transfer to reduce the insufficient thermal dissipation and the elevated temperature caused by irradiation‐induced heating, while retaining their flexibility and portability. A spectrally selective coupling structure consisting of subwavelength hemisphere pattern and distributed Bragg reflector is integrated into FOSCs to collectively enhance out‐coupling of infrared radiation and limit near‐infrared absorption‐induced heat generation, leading to a reduced heat power intensity of 292.5 W cm−2 and the decreased working temperature by 9.6 °C under outdoor sunlight irradiation. The D18:Y6:PC71BM‐based FOSCs achieve a power conversion efficiency of over 17% with a prolonged T80 lifetime as long as one year under real outdoor working conditions. These results represent a new opportunity for enhancing the operational stability of FOSCs.
A spectrally selective coupling structure is integrated into flexible organic solar cells to boost the optical‐thermal radiative transfer in infrared region. The optimized device with efficiency over 17% obtains a 9.6 °C decrease in working temperature under outdoor sunlight irradiation, which prolongs T80 lifetime by over 3 times to as long as one year.
Converting non‐visual light into photocurrent while maintaining high visual transparency is vital for semitransparent organic solar cells (ST‐OSCs) application, yet often challenging over ...insufficient invisible light‐harvesting. Herein, spectrally selective optical manipulation for ST‐OSCs with high visual light transparency and full‐spectral non‐visual light reflection is proposed by matching the optical admittance of ultrathin Ag films using ZnS and MgF2. The reflection of optically enhanced ST‐OSCs at the spectral region beyond the human eye's response spectrum is improved and the transmission in the visual region is simultaneously enhanced. By further integrating an anti‐reflective structure, the optimal structure boosts the average visible transmittance and power conversion efficiency of ST‐OSCs to 44.3% and 12.6%, respectively, yielding a record light utilization efficiency of 5.6%. Corresponding flexible ST‐OSCs with high mechanical stability implies that this work provides a facile and universal strategy for ST‐OSCs aiming at building integrated photovoltaics.
Semitransparent organic solar cells (ST‐OSCs) are constructed with spectrally selective transparent electrodes for high transparency in visual regions and strong light harvesting beyond the human eye's response spectrum. The optical admittance matching induces the ST‐OSCs to achieve a power conversion efficiency of 12.6%, an average visible transmittance of 44.3%, and a record high light utilization efficiency of 5.6%.
Photodiode‐type solar‐blind photodetectors (SBPDs) with the self‐powered feature hold great promise for applications in unattended secure communication, flame detection, and missile warning. However, ...the responsivity of SBPDs is usually limited due to the severe solar‐blind (SB) light extinction in substrates and charge transport layers. Herein, a spectrally selective hole extraction structure (SHE) is proposed for high‐efficiency perovskite SBPDs. The SHE consisting of a tandem Fabry–Perot cavity and energy‐level‐matched hole transport layer endows the device with narrowband absorption in the SB region and optimized charge extraction capability from the CsPbI2Br perovskite. The optimized SHE exhibits a peak transmittance of 27% at 255 nm and a half maximum at full width of 28 nm. Under SB light illumination, the champion device achieves a responsivity of 56.20 mA W−1 and a detectivity (D*) of 2.86 × 1013 Jones, which are the record values among the reported results. The approach demonstrated here paves the way for the optical and electrical design of perovskite photodetectors with spectrally selective detection.
The proposed spectrally selective hole extraction structure consisting of a tandem Fabry–Perot cavity‐based anode enables the selective absorption of solar‐blind light and efficient charge extraction for the self‐powered perovskite solar‐blind photodetector with record responsivity and detectivity.
•Lateral charge collection range of silver nanowires are clarified via microscopic photocurrent images.•Doping LiTFSI in ZnO improves carrier mobility and energy level alignment with AgNWs.•Flexible ...organic solar cells achieve an efficiency of 18.0%.
Although the transparency and sheet resistance of silver nanowire (AgNW) electrodes are comparable to those of rigid indium-tin-oxide electrodes, flexible organic solar cells (FOSCs) are still less efficient than their rigid counterparts. Herein, by recording the microscopic photocurrent images of AgNW-based FOSCs in operation, it has been revealed that the limited lateral charge collection range of AgNW leads to inevitable electrical energy loss. The regulation of carrier mobility and energy level of adjacent ZnO electron transport layer increases the effective collection range of AgNWs by 1.8 times and uniform the electrical potential distribution in FOSCs. The D18:Y6:PC71BM-based FOSCs achieve a power conversion efficiency of approaching 18%. Moreover, the performance drop of large-area FOSCs is significantly reduced due to the improved charge collection on large area scale. This work provides an intuitive insight into the electrical energy loss mechanism of AgNW electrodes and demonstrates an electric field regulation strategy in FOSCs.
Background： The aim of this study was to evaluate the efficacy of ultrasonic features in predicting the malignancy of thyroid nodules in a group of Chinese patients. Methods： In all, 762 patients ...with thyroid nodules （424 malignant and 338 benign） underwent ultrasound （US） check and surgery between March 2011 and July 2014 at Peking University First Hospital were identified. Univariate and receiver operating characteristic （ROC） analyses were performed to calculate the sensitivity, specificity, negative and positive predictive values of each US feature, and the accuracy of their combinations lbr prediction of malignancy. Results： Patients with malignant nodules were younger and without obvious risk history than those in the benign group （P 〈 0.001, P = 0.93 ）. No individual US sign was fully predictive of a malignant lesion. The Youden indexes of irregular margins and hypoechogenicity were the first and second highest in all US features, which were 51.9% and 45.2%, respectively. The sensitivity of solid components （89.7%） and hypoechogenicity （89.2%） and the specificity of taller-than-wide shape （98.5%） and microcalcifications （90.6%） were the first and second highest in all US features. Intranodular flow on a color Doppler examination was a weak predictor of malignancy. Under ROC analysis excepting intranodular flow, the 95% confidence interval （C1） of areas under tile curves of hypoechogenicity and irregular margins with any one of the US features were overlapped that of five-feature combinations （95% CI： 0.850 0.901）. Conclusions： We should be alert with taller-than-wide shape and microcalcifications, lntranodular flow was a weak predictor of malignancy. According to Youden indexes and ROC analysis, irregular margins and hypoechogenicity combined with solid component or taller-than-wide shapes or microcalcifications have a high predicative value for malignant thyroid nodules in Chinese patients.
To summarize the experience of diagnosis and treatment of esophageal leiomyoma.
Clinical data of 52 patients with esophageal leiomyoma were analyzed from 1993 to 2002.
About 54% patients in this ...group had difficulty of food intake. The diagnostic accuracy of gastrointestinal barium meal series, computed tomography, gastric endoscope and endoscopic ultrasonography (EUS) for esophageal leiomyoma was 64% 44% 27% and 90% respectively. All patients received operation, resection of esophageal leiomyoma by videothoracoscopy (VAS) and endoscope were performed in 6, 9 patients respectively. The remaining 37 patients received regular open operation,in whom 32 cases received enucleation of esophageal leiomyoma, 5 cases received partial esophageal resection and esophageal-gastric anastomosis. No serious complications occurred except only one case needed operation again because of bleeding.
EUS is an effective method for diagnosing esophageal leiomyoma. VAS and endoscopic treatment should be considered for suitable cases
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