In recent years, Cu2ZnSn(S,Se)4(CZTSSe) materials have enabled important progress in associated thin‐film photovoltaic (PV) technology, while avoiding scarce and/or toxic metals; however, cationic disorder and associated band tailing fundamentally limit device performance. Cu2BaSnS4(CBTS) has recently been proposed as a prospective alternative large bandgap (~2 eV), environmentally friendly PV material, with ~2% power conversion efficiency (PCE) already demonstrated in corresponding devices. In this study, a two‐step process (i.e., precursor sputter deposition followed by successive sulfurization/selenization) yields high‐quality nominally pinhole‐free films with large (>1 µm) grains of selenium‐incorporated (
Polymeric semiconductors are crucial candidates for the construction of next‐generation flexible and printable electronic devices. By virtue of the successful preparation of monodispersed colloidal solution in orthogonal solvent, poly(3‐hexylthiophene) (P3HT) nanofibers are developed into versatile building blocks for nanoelectronics and their compatibilities are verified with photolithographic lift‐off technology. Then, the joint efforts from both the bottom‐up hierarchical self‐assembly and top‐down self‐alignment technology have led to the realization of lateral asymmetric heterojunctions with resolution better than 1 µm. As a result, planar photovoltaic devices incorporating
- NSF-PAR ID:
- 10363704
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Small
- Volume:
- 18
- Issue:
- 10
- ISSN:
- 1613-6810
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
x = 3) Cu2BaSnS4−x Sex (CBTSSe) for high‐efficiency PV devices. By incorporating Se in the sulfide film, absorber layers with 1.55 eV bandgap, ideal for single‐junction PV, have been achieved within the CBTSSe trigonal structural family. The abrupt transition in quantum efficiency data for wavelengths above the absorption edge, coupled with a strong sharp photoluminescence feature, confirms the relative absence of band tailing in CBTSSe compared to CZTSSe. For the first time, by combining bandgap tuning with an air‐annealing step, a CBTSSe‐based PV device with 5.2% PCE (total area 0.425 cm2) is reported, >2.5× better than the previous champion pure sulfide device. These results suggest substantial promise for the emerging Se‐rich Cu2BaSnS4–x Sex family for high‐efficiency and earth‐abundant PV. -
more » « less
ABSTRACT Block copolymers with donor and acceptor conjugated polymer blocks provide an approach to dictating the donor–accepter interfacial structure and understanding its relationship to charge separation and photovoltaic performance. We report the preparation of a series of donor‐linker‐acceptor block copolymers with poly(3‐hexylthiophene) (P3HT) donor blocks, poly((9,9‐dioctylfluorene)‐2,7‐diyl‐alt‐[4,7‐bis(thiophen‐5‐yl)‐2,1,3‐benzothiadiazole]‐2′,2″‐diyl) (PFTBT) acceptor blocks, and varying lengths of oligo‐ethylene glycol (OEG) chains as the linkers. Morphological analysis shows that the linkers increase polymer crystallinity while a combination of optical and photovoltaic measurements shows that the insertion of a flexible spacer reduces fluorescence quenching and photovoltaic efficiencies of solution processed photovoltaic devices. Density functional theory (DFT) simulations indicate that the linking groups reduce both charge separation and recombination rates, and block copolymers with flexible linkers will likely rotate to assume a nonplanar orientation, resulting in a significant loss of overlap at the donor–linker–acceptor interface. This work provides a systematic study of the role of linker length on the photovoltaic performance of donor–linker–acceptor block copolymers and indicates that linkers should be designed to control both the electronic properties and relative orientations of conjugated polymers at the interface. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.
2018 ,56 , 1135–1143 -
more » « less
Abstract Approaches to control the self‐assembly of aromatic structures to enhance intermolecular electronic coupling are the key to the development of new electronic and photonic materials. Acenes in particular have proven simple to functionalize to induce strong
π ‐stacking interactions, although finer control of intermolecularπ ‐overlap has proven more difficult to accomplish. In this report, we describe how very weak hydrogen bonding interactions can exert profound impact on solid‐state order in solubilized pentacenes, inducing self‐assembly in either head‐to‐tail motifs with strong 2‐Dπ ‐stacking, or head‐to‐head orientations with much weaker, 1‐Dπ ‐stacking arrangements. In order to achieve 3‐Dπ ‐stacking useful for photovoltaic applications, we elaborated a series of diethynyl pentacenes to their trimeric dehydro[18]annulene forms. These large, strongly interacting structures did indeed behave as acceptors in polymer photovoltaic devices. -
more » « less
Abstract Semiconducting mesocrystalline bulk polymer specimens that exhibit near‐intrinsic properties using channel‐die pressing are demonstrated. A predominant edge‐on orientation is obtained for poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) throughout 2 mm‐thick/wide samples. This persistent mesocrystalline arrangement at macroscopic scales allows reliable evaluation of the electronic charge‐transport anisotropy along all three crystallographic axes, with high mobilities found along the π‐stacking. Indeed, charge‐carrier mobilities of up to 2.3 cm2V−1s−1are measured along the π‐stack, which are some of the highest mobilities reported for polymers at low charge‐carrier densities (drop‐cast films display mobilities of maximum ≈10−3cm2V−1s−1). The structural coherence also leads to an unusually well‐defined photoluminescence line‐shape characteristic of an H‐aggregate (measured from the surface perpendicular to the materials flow), rather than the typical HJ‐aggregate feature usually found for P3HT. The approach is widely applicable: to electrical conductors and materials used in n‐type devices, such as poly{[
N ,N ′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt ‐5,5′‐(2,2′‐bithiophene)} (N2200) where the mesocrystalline structure leads to high electron transport along the polymer backbones (≈1.3 cm2V−1s−1). This versatility and the broad applicability of channel‐die pressing signifies its promise as a straightforward, readily scalable method to fabricate bulk semiconducting polymer structures at macroscopic scales with properties typically accessible only by the tedious growth of single crystals. -
more » « less
Abstract Cadmium sulfide (CdS) has received widespread attention as the building block of optoelectronic devices due to its extraordinary optoelectronic properties, low work function, and excellent thermal and chemical stability. Here, a self‐powered flexible photodetector (PD) based on p‐Si/n‐CdS nanowires heterostructure is fabricated. By introducing the pyro‐phototronic effect derived from wurtzite structured CdS, the self‐powered PD shows a broadband response range, even beyond the bandgap limitation, from UV (325 nm) to near infrared (1550 nm) under zero bias with fast response speed. The light‐induced pyroelectric potential is utilized to modulate the optoelectronic processes and thus improve the photoresponse performance. Lasers with different wavelengths have different effects on the self‐powered PDs and corresponding working mechanisms are carefully investigated. Upon 325 nm laser illumination, the rise time and fall time of the self‐powered PD are 245 and 277 µs, respectively, which are faster than those of most previously reported CdS‐based nanostructure PDs. Meanwhile, the photoresponsivity
R and specific detectivityD * regarding to the relative peak‐to‐peak current are both enhanced by 67.8 times, compared with those only based on the photovoltaic effect‐induced photocurrent. The self‐powered flexible PD with fast speed, stable, and broadband response is expected to have extensive applications in various environments.
